The problem happens when MariaDB master replicates writes for only non InnoDB
tables (e.g. writes to MyISAM table(s)). Async slave node, in Galera cluster,
can apply these writes successfully, but it will, in the end, write gtid position in
mysql.gtid_slave_pos table. mysql.gtid_slave_pos table is InnoDB engine, and
this write makes innodb handlerton part of the replicated "transaction".
Note that wsrep patch identifies that write to gtid_slave_pos should not be replicated
and skips appending wsrep keys for these writes. However, as InnoDB was present
in the transaction, and there are replication events (for MyISAM table) in transaction
cache, but there are no appended keys, wsrep raises an error, and this makes the söave
thread to stop.

The fix is simply to not treat it as an error if async slave tries to replicate a write
set with binlog events, but no keys. We just skip wsrep replication and return successfully.

This commit contains also a mtr test which forces mysql.gtid_slave_pos table isto be
of InnoDB engine, and executes MyISAM only write through asyn replication.

There is additional fix for declaring IO and background slave threads as non wsrep.
These threads should not write anything for wsrep replication, and this is just a safeguard
to make sure nothing leaks into cluster from these slave threads.

DbugParse(): removed mutex lock/unlock which should protect file writes only.
And no file writes happen in this function.

DbugFlush(): move mutex_unlock out of this method because fflush() doesn't
need any locking.

Slow stuff like mutex lock/unlock and accessing errno (TLS)
is moved to a more narrow scope.

This PR contains a mtr test for reproducing a failure with replicating create table as select statement (CTAS) through asynchronous mariadb replication to mariadb galera cluster.
The problem happens when CTAS replication contains both create table statement followed by row events for populating the table. In such situation, the galera node operating as mariadb replication slave, will first replicate only the create table part into the cluster, and then perform another replication containing both the create table and row events. This will lead all other nodes to fail for duplicate table create attempt, and crash due to this failure.

PR contains also a fix, which identifies the situation when CTAS has been replicated, and makes further scan in async replication stream to see if there are following row events. The slave node will replicate either single TOI in case the CTAS table is empty, or if CTAS table contains rows, then single bundled write set with create table and row events is replicated to galera cluster.

This fix should keep master server's GTID's for CTAS replication in sync with GTID's in galera cluster.

Make sure that the sort buffers can store atleast one sort key.
This is needed to make sure that all merge buffers are read else
with no sort keys some merge buffers are skipped because the code
makes a conclusion there is no data to be read.

Closes #1106

Problem:
========
CURRENT_TEST: binlog_encryption.rpl_corruption

mysqltest: In included file "./include/wait_for_slave_io_error.inc":
...
At line 72: Slave stopped with wrong error code
**** Slave stopped with wrong error code: 1743 (expected 1595,1913) ****

Analysis:
========
The test emulates the corruption at the various stages of replication for
example in binlog file, in network and in relay log etc. It verifies that all
corruption cases are handled through appropriate error messages.

The test cases which emulate network failure expect following errors.
--ER_SLAVE_RELAY_LOG_WRITE_FAILURE (1595)
--ER_NETWORK_READ_EVENT_CHECKSUM_FAILURE (1743)

Ideally test should expect error codes as 1595 and 1743.
But the test actually waits on incorrect error code 1595,1913

Fix:
===
Added appropriate error code for 'ER_NETWORK_READ_EVENT_CHECKSUM_FAILURE'.
Replaced 1913 with 1743.

MDEV-19376 Repl_semi_sync_master::commit_trx assertion failure: ... || !m_active_tranxs->is_tranx_end_pos(trx_wait_binlog_name, trx_wait_binlog_pos)

The assert indicates that the current transaction got caught uncleaned from
the semisync master's cache when it is signaled to proceed upon its
ack receive.

The reason of missed cleanup turns out to be a flaw in the gtid
connect mode.
A submitted by connecting slave value of its last received event's
binlog file *name* was adopted into
{{Repl_semi_sync_master::m_reply_file_name}} as a part of semisync
initialization.

Notice that the initialization still refines the position part of the
submitted last received event's binlog coordinates.
The master side binlog filename:pos refinement is
specific to the gtid connect mode for purpose of computing the latest
binlog file to resume slave feeding from.
Effectively in the gtid connect mode the computed resumption filename:pos
may appear smaller in which case a new post-connect time committing
transaction may be logged with its filename:pos also less than the
submitted coordinates and that triggers the assert.

Fixed with making the semisync initialization to use the refined filename:pos.
It is guaranteed to be less than any new generated transaction's binlog:pos.

Make sure failure to find mariabackup binary does not terminate
the script silently, terminate with a clear error message instead

The issue here is the wrong estimate of the cardinality of a partial join,
the cardinality is too high because the function table_cond_selectivity()
returns an absurd number 100 while selectivity cannot be greater than 1.

When accessing table t by outer reference t1.a via index we do not perform any
range analysis for t. Yet we see TABLE::quick_key_parts[key] and
TABLE->quick_rows[key] contain a non-zero value though these should have been
remained untouched and equal to 0.

Thus real cause of the problem is that TABLE::init does not clean the arrays
TABLE::quick_key_parts[] and TABLE::>quick_rows[].
It should have done it because the TABLE structure created for any
instance of a table can be reused for many queries.

InnoDB: Assertion failure in file .../dict/dict0dict.cc line ...
InnoDB: Failing assertion: table->can_be_evicted

This fixes a regression that was caused by the fix of MDEV-20621
(commit a41d4297).
MySQL 5.6 (and MariaDB 10.0) introduced eviction of tables from
the InnoDB data dictionary cache. Tables that are connected to
FOREIGN KEY constraints or FULLTEXT INDEX are exempt of the eviction.
With the problematic change, a table that would already be exempt
from eviction due to FOREIGN KEY would cause the problem if there
also was a FULLTEXT INDEX defined on it.

dict_load_table(): Only prevent eviction if table->can_be_evicted holds.

Do not rely on existence of CMakeFiles/${target}.dir directory existence
It is not there for custom targets in Ninja build.

Don't save/restore HP_INFO as it could be changed by a concurrent thread.
different parts of HP_INFO are protected by different mutexes and
the mutex that protect most of the HP_INFO does not protect its open_list
data.

As a bonus, make heap_check_heap() to take const HP_INFO* and not
make any changes there whatsoever.

dict_table_rename_in_cache(): Use strcpy() instead of strncpy(),
because they are known to be equivalent in this case (the length
of old_name was already validated).

mariabackup: Invoke strncpy() with one less than the buffer size,
and explicitly add NUL as the last byte of the buffer.

Do the same that newer branches do and don't include glibc-related headers on non-glibc environment.

In the function prev_record_reads where one finds the different row combinations for a
subset of partial join, it did not take into account the selectivity of tables
involved in the subset of partial join.

Unfortunate DROP TEMPORARY..IF EXISTS on a regular table may allow
subsequent CREATE TABLE statements to steal away the PFS_table_share
instance from the dropped table.

In commit d1e6b0bc
some code was supposed to be modified, but instead
it got duplicated. Remove the duplicated copy.

* use compile_time_assert instead of DBUG_ASSERT

* don't use thd->clear_error(), because
  * the error was already consumed by the error handler, so there is
     nothing to clear
  * it's dangerous to clear errors indiscriminately, if the error came
    from outside of read_statistics_for_tables() it must not be cleared

mysql_insert() first opens all affected tables (which implicitly
starts a transaction in InnoDB), then stat tables.
A failure to open a stat table caused open_tables() to abort
the current stmt transaction (trans_rollback_stmt()). So, from the
server point of view the following ha_write_row()-s happened outside
of a transactions, and the server didn't bother to commit them.

The server has a mechanism to prevent a transaction being
unexpectedly committed or rolled back in the middle of a statement -
if an operation takes place _in a sub-statement_ it cannot change
the transaction state. Operations on stat tables are exactly that -
they are not allowed to change a transaction state. Put them in
a sub-statement to make sure they don't.

following Fedora recommendations (see %systemd_post macro in FC29)
let's do `systemctl preset` on the first installation of the server

This reverts commit 396313d3.

Apply the changes to InnoDB and XtraDB that had been
inadvertently skipped in the merge
commit ae476868

That merge failure sabotaged part of MDEV-20127:
>Revert a problematic auto_increment_increment 'fix' from 2014.
>This involves replacing the MDEV-8827 fix and in 10.1,
>removing some WSREP instrumentation.

The code changes were re-merged manually by executing the following:

 # Get the parent of the problematic merge.
git checkout ae476868^
 # Perform the merge again.
git merge ae476868^2
 # Get the conflict resolution from that merge.
git checkout ae476868 .
 # Note: Any changes to these files were removed (empty diff)!
git diff HEAD storage/{innobase,xtradb}/handler/ha_innodb.cc
 # Apply the code changes:
git diff cf403934^2..MERGE_HEAD \
storage/{innobase,xtradb}/handler/ha_innodb.cc|
patch -p1

Basicaly it's an uninitialized read. 165 is 0xa5 which comes from TRASH_ALLOC()

Fix by calling a class ctor which initializes problematic
TMP_TABLE_PARAM::force_copy_fields field

In debug build, whenever MEMORY table instance gets closed it performs
consistency check without protection. It may cause server crash if
executed concurrently with DML.

Moved consistency check to ha_heap::external_lock(F_UNLCK), so that it
is protected by THR_LOCK.