Add more tests and move SST restore to correct place.

Remove sleeps and unnecessary waits.

The log file is opened as root since commit bb7a70c9, so there is no need
to chown it.

Test changes only.

Add wait conditions.

MDEV-21421 : Galera test sporadic failure on galera.galera_as_slave_gtid_myisam: Result length mismatch

In Galera 4 nodes 1 and 2 are galera nodes and node_3 should be
non galera.

* Remove those tests that will not be supported on that release.
* Make sure that correct tests are disabled and have MDEVs
* Sort test names

This should not be merged upwards.

Partitioning storage now supports MRR but doesn't support Index Condition
Pushdown (aka ICP). This causes counter-intuitive query plans for queries
that use BKA and conditions that depend on index fields:
- If the condition refers to other tables, BKA's variant of ICP is used
   to handle it.
- If the condition depends on this table only, the optimizer will try to
  use regular ICP for it, which will fail because the storage engine
  doesn't support ICP.

Make the optimizer be smarter in the second case: if we were not able to
use regular ICP, use BKA's variant of ICP..

No longer used.

MDEV-21669 InnoDB: Table ... contains <n> indexes inside InnoDB, which is different from the number of indexes <n> defined in the MariaDB

compare_keys_but_name(): do not use KEY_PART_INFO::field for
Field::is_equal(). Following the logic of that code we need to
compare fields of a table. But KEY_PART_INFO::field sometimes
(when key part is shorter than table field) is a different field.
In that case Field::is_equal() returns incorrect result and
problems occur.

KEY_PART_INFO::field may become some strange field in
open_frm_error open_table_from_share(). I think this is an
incorrect logic, some tecnhical debt. I'm not fixing it right now,
because I don't have time. But I'm making Field::field_length
a const class member. Then, the only fishy code which changed that
field requires now a const_cast<>. I'm bringing attention to that
code with it. This change should not affect logic of the
program in any way.

MDEV-20867 - Perform careful review of "Server crashes with BACKUP STAGE and FLUSH TABLE table_name"

Reverted original patch (c2e0a0b1).

For consistency with "LOCK TABLE <table_name> READ" and "FLUSH TABLES
WITH READ LOCK", which are forbidden under "BACKUP STAGE", forbid "FLUSH
TABLE <table_name> FOR EXPORT" and "FLUSH TABLE <table_name> WITH READ
LOCK" as well.

It'd allow consistent fixes for problems like MDEV-18643.

Context involves semicolon batching, and the error starts 10.2
No reproducible examples were made yet, but TCP trace suggests
multiple packets that are "squeezed" together (e.g overlong OK packet
that has a trailer which is belongs to another packet)

Remove thd->get_stmt_da()->set_skip_flush() when processing a batch.
skip_flush stems from the COM_MULTI code, which was checked in during
10.2 (and is never used)

The fix is confirmed to work, when evaluated by bug reporter (one of them)

We never reproduced it locally, with multiple tries
thus the root cause analysis is still missing.

Problem seems to be the fact that we did not enforce correct
applier thread numbers after every command that effects them.
Test changes only.

* Remove those tests that will not be supported on that release.
* Make sure that correct tests are disabled and have MDEVs
* Sort test names

This should not be merged upwards.

Problem seems to be the fact that we did not enforce correct
applier thread numbers after every command that effects them.
Test changes only.

* Remove those tests that will not be supported on that release.
* Make sure that correct tests are disabled and have MDEVs
* Sort test names

This should not be merged upwards.

The symbol SRV_MASTER_PURGE_INTERVAL became unused in
mysql/mysql-server@42f36919584e82c621dbec1e69fd05ab023c54c6
when separate purge threads were introduced in MySQL 5.6.5.

Do not materialize a semi-join nest if it contains a materialized derived
table /view that potentially can be subject to the split optimization.
Splitting of materialization of such nest would help, but currently there
is no code to support this technique.

- n_ext value may be less than dtuple_get_n_ext(dtuple) when PK is being
updated and new record inherits the externally stored fields from
delete mark old record.

- Added the test case in innodb_fts suite
- Updated copyright year in row0mysql.cc

Problem:
=======
After discarding the table, fts_optimize_thread aborts during shutdown.
InnoDB fails to remove the table from fts_optimize_wq and it leads to
the fts_optimize_thread to lookup for the auxiliary table and fails.

Fix:
====
While discarding the fts table, remove the table from fts_optimize_wq.

buf_flush_or_remove_pages(): Only define BUF_LRU_DROP_SEARCH_SIZE
and dependent code when the adaptive hash index has been enabled.

JIRA:https://jira.mariadb.org/browse/MDEV-17292

Closes #1443

Quotes added to output.

For automatic number of opened files limit take into account number of table instances for table cache

MDEV-21616: Server crash when using "SET STATEMENT max_statement_time=0 FOR desc xxx" lead to collapse

Main select should be pushed first.

row_log_table_get_pk_old_col(): For replacing a NULL value for a
column of the being-added primary key, look up the correct
default value, even if columns had been instantly reordered or
dropped earlier. This ought to have been broken ever since
commit 0e5a4ac2 (MDEV-15562).

ha_innobase::commit_inplace_alter_table(): After
ALTER_STORED_COLUMN_ORDER, ensure that the virtual column metadata
will be reloaded also when the table is not being rebuilt.

We need to release global system variables mutex before
doing wsrep_init to avoid race with next show status and
we need to save wsrep_on value as it is changed on wsrep_init.
Added test case.

When wsrep_on is changed to ON we might need to run wsrep_init
if wsrep-provider is set and wsrep is not inited.