for write by another connection

The problem was that if a table was locked in one connection by
LOCK TABLES ... WRITE, REPAIR TABLE or OPTIMIZE TABLE, SHOW CREATE
TABLE from another connection would be blocked. As SHOW CREATE TABLE
only reads metadata about the table, such blocking is not needed.

The problem was that when SHOW CREATE TABLE tried to get a metadata
lock on the table in order to open it, it used the wrong type of
metadata lock request. It used MDL_SHARED_READ which is used when
the intent is to read both table metadata and table data. Instead
it should have used MDL_SHARED_HIGH_PRIO which signifies an intent
to only read metadata.

This patch fixes the problem by making sure SHOW CREATE TABLE uses
the MDL_SHARED_HIGH_PRIO metadata lock request type when trying to
open the table. The patch also fixes a similar problem with the
mysql_list_fields API call.

Test case added to show_check.test.

           during rqg_mdl_deadlock test

The problem was that if two connection threads simultaneously tries
to execute "SET GLOBAL EVENT_SCHEDULER = OFF", one of them could
hang waiting for the scheduler to stop.

The first connection thread would kill the event scheduler thread
and then start waiting for it to exit. The second connection thread
would then find the event scheduler thread in the process of exiting
and also wait for it to exit. However, since the event scheduler 
thread used signal to wake only one waiting thread, the other connection
thread would be left waiting.

This bug was a regression introduced by the fix for Bug#51160.
Before #51160 it was not possible for two connection threads to 
try to stop the event scheduler thread simultaneously.

This patch fixes the problem my making sure the event scheduler
thread uses broadcast to notify all waiters that it is exiting.

No test case added as this would require adding debug sync points
to parts of the code where sync points are currently not used.
The patch has been tested with the non-deterministic test case
from the bug description as well as using the RQG.

DDL no longer aborts mysql_lock_tables(), and hence
we no longer need to support need_reopen flag of this
call. 
Remove the flag, and all the code in the server
that was responsible for handling the case when
it was set. This allowed to simplify: 
open_and_lock_tables_derived(), the delayed thread,
multi-update.

Rename MYSQL_LOCK_IGNORE_FLUSH to MYSQL_OPEN_IGNORE_FLUSH,
since we now only support this flag in open_table().

Rename MYSQL_LOCK_PERF_SCHEMA to MYSQL_LOCK_LOG_TABLE,
to avoid confusion.

Move the wait for the global read lock for cases
when we do updates in SELECT f1() or DO (UPDATE) to 
open_table() from mysql_lock_tables(). When waiting
for the read lock, we could raise need_reopen flag,
which is no longer present in mysql_lock_tables().
Since the block responsible for waiting for GRL
was moved, MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK
was renamed to MYSQL_OPEN_IGNORE_GLOBAL_READ_LOCK.

Use new command line options instead of deprecated and removed ones.

This deadlock could occour betweeen one connection executing
SET GLOBAL EVENT_SCHEDULER= ON and another executing SET GLOBAL
EVENT_SCHEDULER= OFF. The bug was introduced by WL#4738.

The first connection would hold LOCK_event_metadata (protecting
the global variable) while trying to lock LOCK_global_system_variables
starting the event scheduler thread (in THD:init()).

The second connection would hold LOCK_global_system_variables
while trying to get LOCK_event_scheduler after stopping the event
scheduler inside event_scheduler_update().

This patch fixes the problem by not using LOCK_event_metadata to
protect the event_scheduler variable. It is still protected using
LOCK_global_system_variables. This fixes the deadlock as it removes 
one of the two mutexes used to produce it.

However, this patch opens up the possibility that the event_scheduler
variable and the real event_scheduler state can become out of sync
(e.g. variable = OFF, but scheduler running). But this can only
happen under very unlikely conditions - two concurrent SET GLOBAL
statments, with one thread interrupted at the exact wrong moment.
This is preferable to having the possibility of a deadlock.

This patch also fixes a bug where it was possible to exit create_event()
without releasing LOCK_event_metadata if running out of memory during
its exection.

No test case added since a repeatable test case would have required
excessive use of new sync points. Instead we rely on the fact that
this bug was easily reproduceable using RGQ tests.

When building the script directory using a CMake-based build, both the
variables in config.h.cmake (including PLUGINDIR) and the variables in
CMakeList.txt (which includes pkgplugindir).

However, for autotools-based builds, only pkgplugindir is substituted,
which means that the plugin-path is not substituted.

This patch solves the problem by using pkgplugindir, which works on both
CMake-based and autotools-based builds, instead of PLUGINDIR.

Remove unnecessary need_reopen loops.

There are two issues fixed here:

  1. We needed to update the result file, for some of 
     mysqlbinlog_* tests, because now the some padding chars
     are not output anymore.

  2. We needed to change the Field_string::pack so that
     for BINARY types the padding chars are not packed 
     (lengthsp will return full length for these types).

Unquoted ${CMAKE_CPACK_COMMAND} is used in this script.
This variable resolves to cpack's real path with spaces, e.g
 /Applications/CMake 2.6.4-app/Contents/bin/cpack. 
Script fails due to lack of quotes.

Fix is to use quotes around ${CMAKE_CPACK_COMMAND}.

The problem is introduced by WL#4435 "Support OUT-parameters in 
prepared statements".
When a statement that has out parameters was reprepared,
the reprepare request error was ignored, and an
attempt to send out parameters to the client was made.

Since the out parameter list was not initialized in case
of an error, this attempt led to a crash.

Don't try to send out parameters to the client
if an error occurred in statement execution.

- Fixing crash on attempt to create a fulltext index with an utf8mb4 column
- fixing wrong border width  for supplementary characters in mysql client:

  mysql --default-character-set=utf8mb4 -e "select concat(_utf32 0x20000,'a')"

Split rpl_row_charset into:

  - rpl_row_utf16.
  - rpl_row_utf32.

This way these tests can run independently if server supports
either one of the charsets but not both.

Cleaned up rpl_row_utf32 which had a spurious instruction:
-- let $reset_slave_type_conversions= 0

In BUG#51787 we were using the wrong charset to print out the
data. We were using the field charset for the string that would
hold the information. This caused the assertion, because the
string length was not aligned with UTF32 bytes requirements for
storage.

We fix this by using &my_charset_latin1 in the string object
instead of the field->charset(). As a side-effect, we needed to
extend the show_sql_type interface so that it took the field
charset is now passed as a parameter, so that one is able to
calculate the correct field size.

In BUG#51716 we had issues with Field_string::pack and
Field_string::unpack. When packing, the length was incorrectly
calculated. When unpacking, the padding the string would be
padded with the wrong bytes (a few bytes less than it should).

We fix this by resorting to charset abstractions (functions) that
calculate the correct length when packing and pad correctly the
string when unpacking.

LOCK kills the server.

Prohibit FLUSH TABLES WITH READ LOCK application to views or
temporary tables.
Fix a subtle bug in the implementation when we actually
did not remove table share objects from the table cache after 
acquiring exclusive locks.