unconditionally set correct filesystem ownership/permissions for the PAM v2 plugin
in all cases, be it install, reinstall, or upgrade

Use the same select as for usual table list.

- TOI error ignoring fix (wsrep_ignore_apply_errors)

The test for the wsrep_info plugin needs the same flexible wsrep version checking as the tests for Galera (continuation of MDEV-18565 task)

btr_push_update_extern_fields(): Add a parameter for the original number
of fields in the record before btr_cur_trim(). Assume that this function
will only be called for the clustered index, which is the only index
that can contain off-page columns.

trx_undo_prev_version_build(), btr_cur_pessimistic_update():
Only invoke btr_push_update_extern_fields() for the clustered index.

- Added mariadb-# to load_default_groups to all mariadb-# scripts and
  mariadb-binaries.
- Added mariadbd and mariadbd-"version" to load_default_groups for the
  mysqld/mariadb server
- Added mariadb-client to load_default_groups for the mysql/mariadb client

Other things
- Ignored mysql-test/lib/My/SafeProcess/wsrep_check_version
- mysql_install_db will now automatically detect if run from srcdir

Set the garbd_exe variable to empty string to avoid warning about an uninitialized variable when wsrep_provider is not initialized correctly, set to 'none' or when wsrep is switched off

Currently, running mtr with an incorrect (for example, new or
obsolete) version of wsrep_provider (for example, with the 26
version of libgalera_smm.so) leads to the failure of tests in
several suites with vague error diagnostics.

As for the galera_3nodes suite, the mtr also does not effectively
check all the prerequisites after merge with MDEV-18426 fixes.
For example, tests that using mariabackup do not check for presence
of ss and socat/nc. This is due to improper handling of relative
paths in mtr scripts.

In addition, some tests in different suites can be run without
setting the environment variables such as MTR_GALERA_TFMT, XBSTREAM,
and so on.

To eliminate all these issues, this patch makes the following changes:

1. Added auxiliary wsrep_mtr_check utility (which located in the
mysql-test/lib/My/SafeProcess subdirectory), which compares the
versions of the wsrep API that used by the server and by the wsrep
provider library, and it does this comparison safely, without
accessing the API if the versions do not match.

2. All checks related to the presence of mariabackup and utilities
that necessary for its operation transferred from the local directories
of different mtr suites (from the suite.pm files) to the main suite.pm
file. This not only reduces the amount of code and eliminates duplication
of identical code fragments, but also avoids problems due to the inability
of mtr to consider relative paths to include files when checking skip
combinations.

3. Setting the values of auxiliary environment variables that
are necessary for Galera, SST scripts and mariabackup (to work
properly) is moved to the main mysql-test-run.pl script, so as
not to duplicate this code in different suites, and to avoid
partial corrections of the same errors for different suites
(while other suites remain uncorrected).

4. Fixed duplication of the have_file_key_management.inc and
have_filekeymanagement.inc files between different suites,
these checks are also transferred to the top level.

5. Added garbd presence check and garbd path variable.

https://jira.mariadb.org/browse/MDEV-18565

Move test to big_test as it takes significant amount of time and
add wait to get slave threads start and setup to replicate.

In this test we are not interested a real cardinality etc
numbers. We are interested if they are not same in both
galera nodes as they should be.

COM_CHANGE_USER and COM_RESET_CONNECTION commands cause
THD::cleanup() to be called in the middle of command handling.
This causes wsrep client_state sanity checks to fail.

As a fix, temporarily close wsrep client_state before THD::change_user()
is called when handling COM_CHANGE_USER and COM_RESET_CONNECTION,
and restore the state after THD::change_user() returns.

This commit also updates wsrep-lib to version which removes
exception usage in wsrep client_state sanity checks.

ALTER_CHANGE_INDEX_COMMENT: new handler flag added

Compare_keys::EqualButComment: new outcome of compare_keys_but_name()

MDEV-16222 Assertion `0' failed in row_purge_remove_sec_if_poss_leaf on table with virtual columns and indexes

Cause
Stale thd->m_stmt_da->m_sql_errno which is from different invocation.

Fix
Reset error state before attempt to open table.

MDEV-19175 Server crashes in ha_partition::vers_can_native upon INSERT DELAYED into versioned partitioned table

Uninitialized LEX::part_info on ha_partition::vers_can_native().

Another fail fix:

undefined reference to `ZipLoadFile`

MDEV-19866 With a Spider table, a SELECT with WHERE involving primary key breaks following SELECTs (#1356)

Change checking scanning partitions from part_spec to part_info->read_partitions

Added checks of the number of columns of the system tables.
Move install_spider.sql into source code except installing Spider

Put all capabilities in one CapabilityBoundingSet line,
otherwise buggy systemd sets CapabilityBoundingSet=0

MDEV-19486 and one more similar bug appeared because handler::write_row() interface
welcomes to modify buffer by storage engine. But callers are not ready for that
thus bugs are possible in future.

handler::write_row():
handler::ha_write_row(): make argument const

Use on every virtual function override.

ha_innobase: mark a final

ha_innobase::bas_ext(): remove as unused

ha_innobase::get_cascade_foreign_key_table_list: remove as unused

ha_innobase::end_stmt(): merge into ha_innobase::reset()

Since 10.4 requires C++11 capable compiler, gcc sync builtins became
dead code. Remove relevant cmake checks and cleanup include files.

Even though the PAUSE instruction latency was increased from
about 10 to 140 clock cycles in the Intel Skylake microarchitecture,
it seems to be optimal to reduce the amount of subsequently executed
PAUSE instructions not to 1/14, but to 1/2.

Uniformly use the `.git` suffix format

* in --parallel mode don't copy/symlinks plugins individually
  in each forked child's vardir, use the common parent vardir with
  all plugins
* move pam plugin specific code from mysql-test-run.pl to
  suite/plugins/suite.pm

(meaning, if MariaDB is installed system-wide, pam tests
require mtr to be run as mysql user)

fixed in MDEV-19878, here just adding tests