By definition, c_lock->trx->lock.wait_lock==c_lock cannot hold.
That is, the owner transaction of a lock cannot be waiting for that
particular lock. It must have been waiting for some other lock.
Remove the dead code related to that. Also, test c_lock for NULLness
only once.

Refactor lock_grant(). With innodb_lock_schedule_algorithm=VATS
some callers were passing an incorrect parameter owns_trx_mutex
to lock_grant().

lock_grant_after_reset(): Refactored from lock_grant(), without
the call to lock_reset_lock_and_trx_wait().

lock_grant_have_trx_mutex(): A variant of lock_grant() where the
caller already holds the lock->trx->mutex. The normal lock_grant()
will acquire and release lock->trx->mutex.

lock_grant(): Define as a wrapper that will acquire lock->trx->mutex.

lock_rec_queue_validate(): Restore some assertions.

DeadlockChecker::select_victim(): Reduce the WSREP-related diff.

lock_table_create(): Move the WSREP parameter c_lock last,
and make it NULL by default, to avoid the need for a wrapper
function.

lock_table_enqueue_waiting(): Move the WSREP parameter c_lock last.

This is a non-functional change.

Revert the dead code for MySQL 5.7 multi-master replication (GCS),
also known as
WL#6835: InnoDB: GCS Replication: Deterministic Deadlock Handling
(High Prio Transactions in InnoDB).

Also, make innodb_lock_schedule_algorithm=vats skip SPATIAL INDEX,
because the code does not seem to be compatible with them.

Add FIXME comments to some SPATIAL INDEX locking code. It looks
like Galera write-set replication might not work with SPATIAL INDEX.

The merge only covered 10.1 up to
commit 4d248974.

Actually merge the changes up to
commit 0a534348.

Also, remove the unused InnoDB field trx_t::abort_type.

Eliminated last exit() call from libmysqld.

MDEV-14545 Backup fails due to MLOG_INDEX_LOAD record

- Changed the unsupported_redo test case to avoid checkpoint
- Inserting more rows in purge_secondary test case to display evict monitor.

Unlike commit a54abf01 claimed,
the caller of THD::awake() may actually hold the InnoDB lock_sys->mutex.
That commit introduced a deadlock of threads in the replication slave
when running the test rpl.rpl_parallel_optimistic_nobinlog.

lock_trx_handle_wait(): Expect the callers to acquire and release
lock_sys->mutex and trx->mutex.

innobase_kill_query(): Restore the logic for conditionally acquiring
and releasing the mutexes. THD::awake() can be called from inside
InnoDB while holding one or both mutexes, via thd_report_wait_for() and
via wsrep_innobase_kill_one_trx().

            the non-recursive CTE defined with UNION

The problem appears as the columns of the non-recursive CTE weren't renamed.
The renaming procedure was called for recursive CTEs only.

To fix it in the procedure st_select_lex_unit::prepare
With_element::rename_columns_of_derived_unit is called now for both CTEs:
recursive and non-recursive.

ha_innobase::unlock_row(): Use a relaxed version of the
trx_state_eq() debug assertion, because rr_unlock_row()
may be invoked after an error has been already reported
and the transaction has been rolled back.

By definition, c_lock->trx->lock.wait_lock==c_lock cannot hold.
That is, the owner transaction of a lock cannot be waiting for that
particular lock. It must have been waiting for some other lock.
Remove the dead code related to that. Also, test c_lock for NULLness
only once.

The caller of THD::awake() should never hold any InnoDB mutexes,
so we can always acquire lock_sys->mutex and trx->mutex.

MDEV-13549 Fix and re-enable test galera.galera_var_slave_threads

Two changes were made to the test:

1) Suppress warning "Refusing exit for the last slave thread."
   This warning was already suppressed, but on the wrong node.

2) The test occasionally fails because it expects that the
   number of applier threads changes immediately after
   changing the value of ```variable wsrep_slave_threads```.
   Which is not true. This patch turns snippets like this:

   ```
   SET GLOBAL wsrep_slave_threads = x;
   SELECT COUNT(*) = x FROM INFORMATION_SCHEMA.PROCESSLIST WHERE USER = 'system user';
   ```

   Into proper wait_conditions:

   ```
   SET GLOBAL wsrep_slave_threads = x;
   let $wait_condition = SELECT COUNT(*) = x FROM ...;
   --source include/wait_condition.inc
   ```

- Work around for MDEV-13942: Drop spatial index to avoid possible hang

MDEV-15540 fix for MTR tests using wsrep_recover.inc

MDEV-14144 Fix for MTR tests complaining "Query didn't return a result set"

MDEV-13549 Fix for test galera.galera_var_max_ws_rows

MDEV-13549 Fix and re-enable MTR test galera.MW-366

MDEV-13549 Fix and re-enable test galera.galera_bf_abort_for_update

MDEV-13549 Fix and re-enable test galera.MW-286

These tests were also subject to error "Wrong usage of mutex
'LOCK_wsrep_thd' and 'LOCK_thd_kill'".

"mtr func_date_add" failed on 32-bit platforms. Removing a wrong case to "long".
Both values[] and log_10_int[] are arrays of "ulonglong", no cast is needed.

add the test case (the bug was fixed in d390e501)

Refactor get_datetime_value() not to create Item_cache_temporal(),
but do it always in ::fix_fields() or ::fix_length_and_dec().

Creating items at the execution time doesn't work very well with
virtual columns and check constraints that are fixed and executed
in different THDs.

while it should look at the actual field_type() and use get_date()
or get_time() as appropriate.

test case is in the following commit.

Do not assume that it's always item->field_type() - this is not the case
in temporal comparisons (e.g. when comparing DATETIME column with a TIME
literal).

It's a generic function, not using anything from Arg_comparator.
Make it a static function, not a class method, to be able to use
it later without Arg_comparator