Fix clang-cl built

The cause was an uninitalized variable on the slave when reading a dummy
event that can only be generated by the test.

Fixed by ensuring that flag2 is always initialized.
Fixed also some indentation issues and improved comments.

by suppressing Unix only system checks

The test main.mysqltest could crash or hang with
cmake -DWITH_ASAN=ON builds. The reason appears to be
a memory leak, which was found out by manually invoking

echo --replace_regex a > file
ASAN_OPTIONS=log_path=/dev/shm/asan mysqltest ... < file

and then examining the /dev/shm/asan.* file.

commit 121a5e8d revised the function
buf_pool_watch_unset() in such a way that the debug field
buf_page_t::in_page_hash is no longer protected by buf_pool.mutex
and thus not safe to access by the debug assertion in
buf_pool_watch_set().

For now, let us revert the change to buf_pool_watch_unset()
and have it acquire the buf_pool.mutex for a longer time.

MDEV-22030 Don't grant REPLICATION MASTER ADMIN automatically on upgrade from an older JSON user table

Adding a test to check that having a user with REPLICATION SLAVE
privilege is enough to run replication.

Made by Serg.

This was done to both simplify the code and also to be easier to handle
storage engines that are clustered on some other index than the primary
key.

As pk_is_clustering_key() and is_clustering_key now are using only
index_flags, these where removed from all storage engines.

Changes:
- Initalize Aria early to allow it to load mysql.plugin table with --help
- Don't print 'aborting' when doing --help
- Don't write 'loose' error messages on log_warning < 2 (2 is default)
- Don't write warnings about disabled plugings when doing --help
- Don't write aria_log_control or aria log files when doing --help
- When using --help, open all Aria tables in read only mode (safety)
- If aria_init() fails, do a cleanup(). (Frees used memory)
- If aria_log_control is locked with --help, then don't wait 30 seconds
  but instead return at once without initialzing Aria plugin.

MDEV-21604

Added "virtual" low level write function encrypt_or_write that is set
to point to either normal or encrypted write functions.

This patch also fixes a possible memory leak if writing to binary log fails.

MDEV-21605 Clean up and speed up interfaces for binary row logging
MDEV-21617 Bug fix for previous version of this code

The intention is to have as few 'if' as possible in ha_write() and
related functions. This is done by pre-calculating once per statement the
row_logging state for all tables.

Benefits are simpler and faster code both when binary logging is disabled
and when it's enabled.

Changes:
- Added handler->row_logging to make it easy to check it table should be
  row logged. This also made it easier to disabling row logging for system,
  internal and temporary tables.
- The tables row_logging capabilities are checked once per "statements
  that updates tables" in THD::binlog_prepare_for_row_logging() which
  is called when needed from THD::decide_logging_format().
- Removed most usage of tmp_disable_binlog(), reenable_binlog() and
  temporary saving and setting of thd->variables.option_bits.
- Moved checks that can't change during a statement from
  check_table_binlog_row_based() to check_table_binlog_row_based_internal()
- Removed flag row_already_logged (used by sequence engine)
- Moved binlog_log_row() to a handler::
- Moved write_locked_table_maps() to THD::binlog_write_table_maps() as
  most other related binlog functions are in THD.
- Removed binlog_write_table_map() and binlog_log_row_internal() as
  they are now obsolete as 'has_transactions()' is pre-calculated in
  prepare_for_row_logging().
- Remove 'is_transactional' argument from binlog_write_table_map() as this
  can now be read from handler.
- Changed order of 'if's in handler::external_lock() and wsrep_mysqld.h
  to first evaluate fast and likely cases before more complex ones.
- Added error checking in ha_write_row() and related functions if
  binlog_log_row() failed.
- Don't clear check_table_binlog_row_based_result in
  clear_cached_table_binlog_row_based_flag() as it's not needed.
- THD::clear_binlog_table_maps() has been replaced with
  THD::reset_binlog_for_next_statement()
- Added 'MYSQL_OPEN_IGNORE_LOGGING_FORMAT' flag to open_and_lock_tables()
  to avoid calculating of binary log format for internal opens. This flag
  is also used to avoid reading statistics tables for internal tables.
- Added OPTION_BINLOG_LOG_OFF as a simple way to turn of binlog temporary
  for create (instead of using THD::sql_log_bin_off.
- Removed flag THD::sql_log_bin_off (not needed anymore)
- Speed up THD::decide_logging_format() by remembering if blackhole engine
  is used and avoid a loop over all tables if it's not used
  (the common case).
- THD::decide_logging_format() is not called anymore if no tables are used
  for the statement. This will speed up pure stored procedure code with
  about 5%+ according to some simple tests.
- We now get annotated events on slave if a CREATE ... SELECT statement
  is transformed on the slave from statement to row logging.
- In the original code, the master could come into a state where row
  logging is enforced for all future events if statement could be used.
  This is now partly fixed.

Other changes:
- Ensure that all tables used by a statement has query_id set.
- Had to restore the row_logging flag for not used tables in
  THD::binlog_write_table_maps (not normal scenario)
- Removed injector::transaction::use_table(server_id_type sid, table tbl)
  as it's not used.
- Cleaned up set_slave_thread_options()
- Some more DBUG_ENTER/DBUG_RETURN, code comments and minor indentation
  changes.
- Ensure we only call THD::decide_logging_format_low() once in
  mysql_insert() (inefficiency).
- Don't annotate INSERT DELAYED
- Removed zeroing pos_in_table_list in THD::open_temporary_table() as it's
  already 0

MDEV-21606 Improve update handler (long unique keys on blobs)
MDEV-21470 MyISAM and Aria start_bulk_insert doesn't work with long unique
MDEV-21606 Bug fix for previous version of this code
MDEV-21819 2 Assertion `inited == NONE || update_handler != this'

- Move update_handler from TABLE to handler
- Move out initialization of update handler from ha_write_row() to
  prepare_for_insert()
- Fixed that INSERT DELAYED works with update handler
- Give an error if using long unique with an autoincrement column
- Added handler function to check if table has long unique hash indexes
- Disable write cache in MyISAM and Aria when using update_handler as
  if cache is used, the row will not be inserted until end of statement
  and update_handler would not find conflicting rows.
- Removed not used handler argument from
  check_duplicate_long_entries_update()
- Syntax cleanups
  - Indentation fixes
  - Don't use single character indentifiers for arguments

- Only indentation changes in sql_rename.cc
- Ignore some WSREP error messages when there isn't a internet connection
- Force restart of stat_tables_part.test to make result stable
- Fixed compiler warnings in CONNECT

MDEV-19964 S3 replication support

Added new configure options:
s3_slave_ignore_updates
"If the slave has shares same S3 storage as the master"

s3_replicate_alter_as_create_select
"When converting S3 table to local table, log all rows in binary log"

This allows on to configure slaves to have the S3 storage shared or
independent from the master.

Other thing:
Added new session variable '@@sql_if_exists' to force IF_EXIST to DDL's.

- rename PFS specific rebind_psi() to generic rebind()
- call rebind independently of PFS compilation status
- allow rebind() return an error

MDEV-21988: Assertion failure mysqld: bool trans_commit_stmt(THD*): Assertion `thd->in_active_multi_stmt_transaction() || thd->m_transaction_psi == __null' failed. (#1476)

Set temporary `SERVER_STATUS_IN_TRANS` so assert is not triggered in `trans_commit_stmt`.

The test failed to specify default-character-set when
invoking the client. The compile-time default parameters of the
client could be overridden by configuration files in /etc/mysql.
Let us explicitly specify --default-character-set.

main.mysqlhotcopy_myisam cannot find mysqlhotcopy tool

wsrep scripts are not executable in CMAKE_CURRENT_BINARY_DIR

* generate and install mysql_config
* symlink mariadb_config (from C/C) to mariadb-config

also:
* .gitignore generated mariadb-config.1
* remove obsolete compiler flag from C/C

This reverts commit 5d1b8f41.

because since 306e439c manpages use troff aliases
instead of symlinks, so they should not be symlinked.

Drop excess jobs while still making sure there is a good variation of
running all test suites, gcc and clang versions.

Also introduce testing on architectures arm64 and ppc64le.

- Properly define build dependencies via addons/homebrew, but still keep
  secondary Homebrew run until OS X builds fully work.
- Remove references to OS X bugs that are already closed.
- As long as the OS X build does not work, it is enough to attempt to run
  just one of them, no need for many in parallel. It will just waste
  resources and slow down the job from finishing quickly.

This further simplifies and cleans up the Travis-CI file without making
any major functional changes.

With this structure .travis.yml is much easier to read and thanks to the
added documentation next developers are less likely to mess it up again
as they can more easily see how the jobs matrix work.

Number of jobs:
- before: 33 (with 7 ignored)
- after:  33 (with 7 ignored)

This partially reverts commits c12609dd and 193bc89a.

Remove unnecessary dependencies that nothing uses: dpatch libzmq-dev

Install extra build dependencies from a PPA specifically tailored for
Travis-CI use and which ensures all architectures are supported (in this
case s390x is needed and was not available from mariadb.org repos).

Validated with https://config.travis-ci.com/explore

This is first step in refactoring the Travis-CI file, which had become a
mess. This commit has no functional changes, just syntactical cleanup
and simplification.

Dependencies list has not changes, it is just sorted alphabetically so
it is easier to compare to e.g. debian/control file list.

innodb_init_params(): make sure that srv_n_log_files == 1 always