semisync plugin and setting rpl_semi_sync_master_enabled

There was race condition between INSTALL PLUGIN and SET. It was caused by a
gap in INSTALL PLUGIN when plugin variables were registered but not fully
initialized. Accessing such variables concurrently may reference uninitialized
memory, specifically sys_var_pluginvar::plugin.

Fixed by initializing sys_var_pluginvar::plugin early, before variable is
registered.

           semisync plugin and setting rpl_semi_sync_master_enabled

Cleanup:
Removed my_intern_plugin_lock() and my_intern_plugin_lock_ci() wrappers. They
were obsoleted by revision f56dd32b.

instead of running them only when ssl is not compiled in

"Range Checked for Each Record" should be only employed when the other
option would be cross-product join (i.e. the other option is so bad that
we hardly risk anything).

Previous logic was: use RCfER if there are no possible quick selects, or
quick select would read > 100 rows. Also, it didn't always work as
expected due to range optimizer changing table->quick_keys and us
looking at sel->quick_keys.

Another angle is that recent versions have enabled use of Join Buffering
in e.g. outer joins. This further reduces the range of cases where RCfER
should be used.

We are still unable to estimate the cost of RCfER with any precision, so
now changing the condition of "no quick select or quick->records> 100"
to a hopefully better condition "no quick select or quick would cost more
than full table scan".

Using --ssl-verify-server-cert and --ssl[-*] implies that
the ssl connection is required. The mysql client will now print an error if ssl
is required, but the server can not handle a ssl connection.

MDEV-7695 MariaDB - ssl - fips: can not connect with --ssl-cipher=DHE-RSA-AES256-SHA - handshake failure

Change 512bit DH key to 1024bit to meet FIPS requirements

Changing the error message to:
 "...from type 'decimal(0,?)/*old*/' to type ' 'decimal(10,7)'..."
So it's now clear that the master data type is OLD decimal.

Removing Item_cache::used_table_map, Item_cache::used_tables() and
Item_cache::set_used_tables(). Using the same inherited from
Item_basic_constant implementations instead.

remove/replace deprecated options

   More fixes to assure the order of queries in the log.

  This test also should be fixed - delay added so the connection
  event doesn't happen before the query.

   Connection event can happen before the query ends. Added a delay to
   confirm the order.

  Fhe GEOMETRY field should be handled just as the BLOB field. So that was fiexed in field_conv.
  One additional bug was found and fixed meanwhile - thet the geometry field subtypes
  should also be merged for UNION command.

  The MYSQL_AUDIT_NOTIFY_CONNECTION_CONNECT() call moved to the login_connection()
  function. So that it'll be invoked in any thread handling mode.

        If the SET PASSWORD query doesn't have the password string,
        the parsing of it can fail. It manifested first in MySQL 5.6 as
        it started to hide password lines sent to the plugins.
        Fixed by checking for that case.

   Symbols like TAB or NEWLINE should be escaped, which was
        forgotten in one place.

Check that leaf table list is really built before storing it.

Server may crash if sanity checks of COLUMN_GET() fail.

COLUMN_GET() description generator expects parent CAST item, which may not have
been created due to failure of sanity checks. Then further attempt to report
an error may crash the server.

Fixed COLUMN_GET() description generator to handle such case.

Factory timezone is supposed "For companies who don't want to put time zone
specification in their installation procedures. When users run date, they'll get
the message. Also useful for the "comp.sources" version."

This "message" is exposed as timezone abbreviation, which is supposed to be
short and thus may cause generated INSERT statements to fail.

Do not attempt to load Factory timezone.

Fixed that ALTER VIEW ALGORITHM=UNDEFINED behaved as if algorithm was not
specified.

update tests

When truncating a table's partition, we also need to invalidate the
query cache for it.

treated by git as text files.

Marking all MyISAM files as binary in .gitattributes: (*.frm, *.MYD, *.MYI)

MDEV-8267 Add /*old*/ comment into I_S.COLUMN_TYPE for old DECIMAL

MDEV-7906: InnoDB: Failing assertion: prebuilt->sql_stat_start || trx->state == 1 on concurrent multi-table update

Analysis: Problem is that SQL-layer calls handler API after storage
engine has already returned error state. InnoDB does internal
rollback when it notices transaction error (e.g. lock wait timeout,
deadlock, etc.) and after this transaction is not naturally in
correct state to continue.

Fix: Do not continue fetch operations if transaction is not started.

change the test case to be deterministic
(while still sufficient to test a bug)