Backported patch from 10.3 that allows one to remove short .frm files

dict_stats_process_entry_from_defrag_pool(): Release the mutex

Follow-up fix to MDEV-13201 Assertion `srv_undo_sources || ...` failed on shutdown during DDL operation

Introduce the debug flag trx_t::persistent_stats to suppress the
assertion for the updates of persistent statistics during fast
shutdown.

dict_stats_exec_sql(): Do execute the statement even though shutdown
has been initiated.

dict_stats_exec_sql(): Expect the caller to always provide a transaction.
Remove some redundant assertions. The caller must hold dict_sys->mutex,
but holding dict_operation_lock is only necessary for accessing
data dictionary tables, which we are not accessing.

dict_stats_save_index_stat(): Acquire dict_sys->mutex
for invoking dict_stats_exec_sql().

dict_stats_save(), dict_stats_update_for_index(), dict_stats_update(),
dict_stats_drop_index(), dict_stats_delete_from_table_stats(),
dict_stats_delete_from_index_stats(), dict_stats_drop_table(),
dict_stats_rename_in_table_stats(), dict_stats_rename_in_index_stats(),
dict_stats_rename_table(): Use a single caller-provided
transaction that is started and committed or rolled back by the caller.

dict_stats_process_entry_from_recalc_pool(): Let the caller provide
a transaction object.

ha_innobase::open(): Pass a transaction to dict_stats_init().

ha_innobase::create(), ha_innobase::discard_or_import_tablespace():
Pass a transaction to dict_stats_update().

ha_innobase::rename_table(): Pass a transaction to
dict_stats_rename_table(). We do not use the same transaction
as the one that updated the data dictionary tables, because
we already released the dict_operation_lock. (FIXME: there is
a race condition; a lock wait on SYS_* tables could occur
in another DDL transaction until the data dictionary transaction
is committed.)

ha_innobase::info_low(): Pass a transaction to dict_stats_update()
when calculating persistent statistics.

alter_stats_norebuild(), alter_stats_rebuild(): Update the
persistent statistics as well. In this way, a single transaction
will be used for updating the statistics of a whole table, even
for partitioned tables.

ha_innobase::commit_inplace_alter_table(): Drop statistics for
all partitions when adding or dropping virtual columns, so that
the statistics will be recalculated on the next handler::open().
This is a refactored version of Oracle Bug#22469660 fix.

RecLock::add_to_waitq(), lock_table_enqueue_waiting():
Do not allow a lock wait to occur for updating statistics
in a data dictionary transaction, such as DROP TABLE. Instead,
return the previously unused error code DB_QUE_THR_SUSPENDED.

row_merge_lock_table(), row_mysql_lock_table(): Remove dead code
for handling DB_QUE_THR_SUSPENDED.

row_drop_table_for_mysql(), row_truncate_table_for_mysql():
Drop the statistics as part of the data dictionary transaction.
After TRUNCATE TABLE, the statistics will be recalculated on
subsequent ha_innobase::open(), similar to how the logic after
the above-mentioned Oracle Bug#22469660 fix in
ha_innobase::commit_inplace_alter_table() works.

btr_defragment_thread(): Use a single transaction object for
updating defragmentation statistics.

dict_stats_save_defrag_stats(), dict_stats_save_defrag_stats(),
dict_stats_process_entry_from_defrag_pool(),
dict_defrag_process_entries_from_defrag_pool(),
dict_stats_save_defrag_summary(), dict_stats_save_defrag_stats():
Add a parameter for the transaction.

dict_stats_empty_table(): Make public. This will be called by
row_truncate_table_for_mysql() after dropping persistent statistics,
to clear the memory-based statistics as well.

Part #2: Don't use the new code for the clustered PK, it is handled
in the special way right above.

TABLE_SHARE::init_from_binary_frm_image() calls handler_file->index_flags()
before it has set TABLE_SHARE::primary_key (it is 0 while it should be
MAX_KEY in my example).
This causes MyRocks to report wrong index flags (it thinks it's a PK while
it is not), which causes invalid query plans later on.

Do the only thing that seems feasible: adjust field->part_of key to have
correct value in ha_rocksdb::open.

Part#1: Set field->part_of_key correctly for PK fields.

MDEV-14587 dict_stats_process_entry_from_defrag_pool() fails to call dict_table_close() when index==NULL

dict_stats_process_entry_from_defrag_pool(): Simplify the logic,
and always call dict_table_close() when dict_table_open() returned
a non-NULL handle.

MDEV-13670/MDEV-14550 Error log flood :  "InnoDB: page_cleaner: 1000ms intended loop took N ms. The settings might not be optimal."

Silence the error log output that was introduced in MySQL 5.7
(MariaDB 10.2.2) if log_warnings=2 or less.

We should still figure out what these messages really indicate
and how to solve the problems.

pc_sleep_if_needed(): Add a parameter for the current time,
so that there will be fewer successive calls to ut_time_ms()
with no I/O between them.

buf_flush_page_cleaner_coordinator(): Exit the first loop
whenever shutdown has been requested. At the start of the loop,
call ut_time_ms() only once. Do not display the message if
log_warnings=2 or less.

The function dict_stats_update_if_needed() replaced
row_update_statistics_if_needed(). Adjust the comments accordingly.

Problem was that Binlog_checkpoint can happen at random times.
Fixed by not write binlog_checkpoint for the rpl_log test.

Other things:
- Removed not used variable "$keep_gtid_events"
- Added option for show_binlog_events to skip binlog_checkpoint

Originally only symbols withing [] where resolved. Now we resolve
symbols also withing (+...)

To make it easier to see where the resolved symbol comes from, we
resolve the symbol 'in place' instead of just printing the resolved
symbol alone.

srv_purge_wakeup(): If thd_destructor_proxy has initiated the first
step of shutdown, ensure that all purge threads terminate.

logs_empty_and_mark_files_at_shutdown(): Add a debug assertion.
(The purge threads should have been shut down already before this step.)

(possibly intermittent) checksum mismatch.

is detected.

The checksum mismatch can be due to partial write, thus retry the read

Window is a reserved keyword according to SQL Standard 2016. However, we
can make the grammar slightly flexible by allowing WINDOW keyword everywhere
except table aliases. Change yacc grammar to separate between all keywords
and table_alias keywords.

1. Removing data type specific constants from enum_item_param_state,
   adding SHORT_DATA_VALUE instead.
2. Replacing tests for Item_param::state for the removed constants to
   tests for Type_handler::cmp_type() against {INT|REAL|TIME|DECIAML}_RESULT.
   Deriving Item_param::PValue from Type_handler_hybrid_field_type,
   to store the data type handler of the current value of the parameter.

3. Moving Item_param::decimal_value and Item_param::str_value_ptr
   to Item_param::PValue. Adding Item_param::PValue::m_string
   and changing Item_param to use it to store string values,
   instead of Item::str_value. The intent is to replace Item_param::value
   to a st_value based implementation in the future, to avoid duplicate code.
   Adding a sub-class Item::PValue_simple, to implement
   Item_param::PValue::swap() easier.
   Remaming Item_basic_value::fix_charset_and_length_from_str_value()
   to fix_charset_and_length() and adding the "CHARSET_INFO" pointer
   parameter, instead of getting it directly from item->str_value.charset().
   Changing Item_param to pass value.m_string.charset() instead
   of str_value.charset().
   Adding a String argument to the overloaded
   fix_charset_and_length_from_str_value() and changing Item_param
   to pass value.m_string instead of str_value.

4. Replacing the case in Item_param::save_in_field() to a call
   for Type_handler::Item_save_in_field().

5. Adding new methods into Item_param::PValue:
   val_real(), val_int(), val_decimal(), val_str().
   Changing the corresponding Item_param methods
   to use these new Item_param::PValue methods
   internally. Adding a helper method
   Item_param::can_return_value() and removing
   duplicate code in Item_param::val_xxx().

6. Removing value.set_handler() from Item_param::set_conversion()
   and Type_handler_xxx::Item_param_set_from_value().
   It's now done inside Item_param::set_param_func(),
   Item_param::set_value() and Item_param::set_limit_clause_param().

7. Changing Type_handler_int_result::Item_param_set_from_value()
   to set max_length using attr->max_length instead of
   MY_INT64_NUM_DECIMAL_DIGITS, to preserve the data type
   of the assigned expression more precisely.

8. Adding Type_handler_hybrid_field_type::swap(),
   using it in Item_param::PValue::swap().

9. Moving the data-type specific code from
   Item_param::query_val_str(), Item_param::eq(),
   Item_param::clone_item() to
   Item_param::value_query_type_str(),
   Item_param::value_eq(), Item_param::value_clone_item(),
   to split the "state" dependent code and
   the data type dependent code.
   Later we'll split the data type related code further
   and add new methods in Type_handler. This will be done
   after we replace Item_param::PValue to st_value.

10. Adding asserts into set_int(), set_double(), set_decimal(),
   set_time(), set_str(), set_longdata() to make sure that
   the value set to Item_param corresponds to the previously
   set data type handler.

11. Adding tests into t/ps.test and suite/binlog/t/binlog_stm_ps.test,
   to cover Item_param::print() and Item_param::append_for_log()
   for LIMIT clause parameters.
   Note, the patch does not change the behavior covered by the new
   tests. Adding for better code coverage.

12. Adding tests for more precise integer data type in queries like this:
    EXECUTE IMMEDIATE
     'CREATE OR REPLACE TABLE t1 AS SELECT 999999999 AS a,? AS b'
      USING 999999999;
    The explicit integer literal and the same integer literal
    passed as a PS parameter now produce columns of the same data type.
    Re-recording old results in ps.result, gis.result, func_hybrid_type.result
    accordingly.

- get rid of casts between int and HANDLE.
- store file descriptor in TP_connection_generic to get
rid of multiple mysql_socket_getfd(c->thd->net.vio->mysql_socket))

Also support named pipes (no reason not to support, since it is easy)

mariabackup fails to builds with PFS disabled. The reason was missing include,
which was included by PFS otherwise.

# Conflicts:
#	storage/innobase/include/os0file.h