where it was forgotten to remove them.

The convert_constant_item function converts a constant to integer using
field for condition like 'field = a_constant'. In some cases the
convert_constant_item is called for a subquery when outer select is already
being executed, so convert_constant_item saves field's value to prevent its
corruption. For EXPLAIN and at the prepare phase field's value isn't
initialized yet, thus when convert_constant_item tries to restore saved
value it fails assertion.

Now the convert_constant_item doesn't save/restore field's value if it's
haven't been read yet. Outer constant values are always saved.

mysql-test/r/explain.result:
  Added a test case for the bug#37870.
mysql-test/t/explain.test:
  Added a test case for the bug#37870.
sql/item_cmpfunc.cc:
  Bug#37870: Usage of uninitialized value caused failed assertion.
  Now the convert_constant_item doesn't save/restore field's value if it's
  haven't been read yet. Outer constant values are always saved.

  Bug#39848 events_bugs fails sporadically on pushbuild
            (missing rows in table event_log)
     Details: Reimplement the subtest for BUG 28924
              - check if the number of rows within the table
                event_log changes but don't print rows
                because the number varies depending on
                load on testing box
              - shift DROP USER befor DROP EVENT
                = Subtest fits again to old bug
              - remove no more needed comments + variables
  Bug#39863 events_bugs fails sporadically on pushbuild 
            (extra processes in I_S.PROCESSLIST)
     Details: Abort with appropriate message to the protocol if
              release_lock() does not has the intended effect.
              This cannot prevent problems caused by the probably
              buggy release_lock() but it reveals if we had a
              problem in this area.
  Bug#39978 main.events_bugs does not clean up
     Detail: Restore global.event_scheduler = ON at end of test
  Bug#39569 events_bugs fails sporadically on pushbuild
            (should have failed with errno 1539)
     Detail: Set $wait_timeout to 4 instead of 2
- Fix two instabilities (result sets pulled from processlist in
  subtest for bug 16407) which were found during tests with high
  parallel I/O load
- Minor improvements of formatting
  Details:
  - Add comments
  - Remove tabs and trailing blanks
  - Add line breaks for better readability

updating two test results.

mysql-test/suite/rpl/r/rpl_row_basic_2myisam.result:
  results changed.
mysql-test/suite/rpl_ndb/r/rpl_row_basic_7ndb.result:
  results changed.

correct text describing the --plugin-load option to mysqld

sql/mysqld.cc:
  correct text describing the --plugin-load option to mysqld

The partitioning clause is only a very long single line, which is very
hard to interpret for a human. This patch breaks the partitioning
syntax into one line for the partitioning type, and one line per
partition/subpartition.

mysql-test/r/information_schema_part.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/r/partition.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/r/partition_archive.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/r/partition_datatype.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/r/partition_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/r/partition_mgm.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/r/partition_mgm_err.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/r/partition_not_windows.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/r/partition_range.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/r/partition_symlink.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/ndb/r/ndb_partition_key.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/ndb/r/ndb_partition_range.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/ndb_team/r/ndb_dd_backuprestore.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/inc/partition_directory.inc:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Changed partitioning clause format for verifying the new output format.
mysql-test/suite/parts/r/ndb_dd_backuprestore.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/part_supported_sql_func_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/part_supported_sql_func_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/part_supported_sql_func_ndb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter1_1_2_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter1_1_2_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter1_1_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter1_1_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter1_2_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter1_2_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter2_1_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter2_1_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter2_2_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter2_2_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter3_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter3_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter4_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_alter4_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_auto_increment_archive.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_auto_increment_blackhole.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_auto_increment_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_auto_increment_memory.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_auto_increment_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_auto_increment_ndb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_basic_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_basic_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_basic_symlink_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_basic_symlink_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_bit_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_bit_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_bit_ndb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_char_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_char_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_datetime_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_datetime_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_decimal_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_decimal_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_engine_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_engine_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_engine_ndb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_float_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_float_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_int_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_int_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_int_ndb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc0_archive.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc0_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc0_memory.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc0_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc0_ndb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc1_archive.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc1_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc1_memory.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc1_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc1_ndb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc2_archive.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc2_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc2_memory.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc2_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_mgm_lc2_ndb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_special_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_special_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_syntax_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/partition_syntax_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/parts/r/rpl_partition.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/rpl/r/rpl_extraCol_innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/rpl/r/rpl_extraCol_myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/rpl/r/rpl_innodb_bug28430.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/rpl/r/rpl_row_basic_8partition.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/rpl_ndb/r/rpl_ndb_2innodb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/rpl_ndb/r/rpl_ndb_2myisam.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/rpl_ndb/r/rpl_ndb_dd_partitions.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/rpl_ndb/r/rpl_ndb_extraCol.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/rpl_ndb/r/rpl_ndb_innodb2ndb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/suite/rpl_ndb/r/rpl_ndb_myisam2ndb.result:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Updated test result due to the new partitioning clause output format.
mysql-test/t/partition.test:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Added small tests for for the new partitioning clause output format.
mysql-test/t/partition_mgm.test:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Added small tests for for the new partitioning clause output format.
sql/sql_partition.cc:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Changed formatting of the partitioning clause from single line into
  multiple indented lines
sql/sql_show.cc:
  Bug#14326: No formatting of partitioning clause in SHOW CREATE TABLE output
  
  Changed formatting of the partitioning clause from single line into
  multiple indented lines

TRUNCATE TABLE for InnoDB tables returned a count showing an approximation
of the number of rows affected to gain efficiency.
Now the statement always returns 0 rows affected for clarity.

sql/sql_delete.cc:
  * Set row count to 0 if auto increment was reset which can happen
  if TRUNCATE TABLE was issued.

a test on the bug page does not reveal the problem with the latest trees.

Adding the test to the rpl suite in order to monitor regression.


mysql-test/extra/rpl_tests/rpl_row_basic.test:
  a regression test for the bug#38230.
mysql-test/suite/rpl/r/rpl_row_basic_3innodb.result:
  results changed.

implicit command which isn't completed immediately.


mysql-test/r/status2.result:
  * Moved disconnect command to avoid race.
mysql-test/t/status2.test:
  * Moved disconnect command to avoid race.

Problem was that partitioning cached the table flags.
These flags could change due to TRANSACTION LEVEL changes.
Solution was to remove the cache and always return the table flags
from the first partition (if the handler was initialized).

mysql-test/r/partition_innodb_stmt.result:
  Bug#39084: Getting intermittent errors with statement-based binary logging
  
  New test result file.
mysql-test/t/partition_innodb_stmt.test:
  Bug#39084: Getting intermittent errors with statement-based binary logging
  
  New test file.
sql/ha_partition.cc:
  Bug#39084: Getting intermittent errors with statement-based binary logging
  
  Removed m_table_flags, and added m_handler_status.
  Added checks that all partitions have the same
  table flags.
  Moved some variable initializations.
  Updated some comments.
  Fixed typo initialise -> initialize
  Changed HA_EXTTA_NO_READCHECK to do nothing, since it
  is only used in ha_open, which is called for every
  partition in ::open anyway.
sql/ha_partition.h:
  Bug#39084: Getting intermittent errors with statement-based binary logging
  
  Removed m_table_flags, and added m_handler_status.
  Always return the first partitions table flags, instead of using
  cached table flags.
  Added define of enabled/disabled partitioning table flags
  Fixed type initialise -> initialize
  Updated some comments.
sql/handler.cc:
  Bug#39084: Getting intermittent errors with statement-based binary logging
  
  Fixed type initialise -> initialize.
sql/handler.h:
  Bug#39084: Getting intermittent errors with statement-based binary logging
  
  Added comment to understand where the cached value is set.

    #ifdef HAVE_purify removed

per-file comments:
  mysql-test/t/partition_not_windows.test
Bug#39102 valgrind build does not compile in realpath, which make DATA/INDEX DIR fail 
    test reenabled

  mysys/my_symlink.c
Bug#39102 valgrind build does not compile in realpath, which make DATA/INDEX DIR fail 
  superfluous ifdef removed, comments fixed

A string buffers which were included in the 'view' data structure
were allocated on the stack, causing an invalid pointer when used
after the function returned.
The fix: use copy of values for view->md5 & view->queries


mysql-test/r/view.result:
  test result
mysql-test/t/view.test:
  test case
sql/sql_view.cc:
  A string buffers which were included in the 'view' data structure
  were allocated on the stack, causing an invalid pointer when used
  after the function returned.
  The fix: use copy of values for view->md5 & view->queries

      
The convert_constant_item function converts a constant to integer using
field for condition like 'field = a_constant'. When the convert_constant_item
is called for a subquery the outer select is already being executed, so
convert_constant_item saves field's value to prevent its corruption.
For EXPLAIN field's value isn't initialized thus when convert_constant_item
tries to restore saved value it fails assertion.
      
Now the convert_constant_item doesn't save/restore field's value
for EXPLAIN.


mysql-test/r/explain.result:
  Added a test case for the bug#37870.
mysql-test/t/explain.test:
  Added a test case for the bug#37870.
sql/item_cmpfunc.cc:
  Bug#37870: Usage of uninitialized value caused failed assertion.
  Now the convert_constant_item doesn't save/restore field's value
  for EXPLAIN.

The abi_check target instroduced as part of WL#4380 verifies
changes to mysql.h. mysql.h in turn includes mysql_version.h.
mysql_version.h is a file that is generated during the configure
phase. We must ensure that mysql_version.h is cleaned only during
distclean and not during clean.

include/Makefile.am:
  This file contains the following changes
  
  1) Moves the cleaning of mysql_version.h from the clean
     phase to the distclean phase.
  
  2) Removes mysql_version.h.in from noinst_HEADERS, this
     entry was reduntant since by virtue of inclusion of
     mysql_version.h mysql_version.h.in is already included.