Remove stale references to srv_sys.sys_threads and srv_sys.mutex
that were removed in
commit 5e62b6a5.

We can simply use C++11 std::atomic for avoiding undefined behaviour
related to concurrent stores to a shared variable. On most if not all
ISAs, std::memory_order_relaxed loads and stores will not really
differ from non-atomic loads or stores.

In fts_optimize_remove_table(), InnoDB tries to access the
fts_optimize_wq after shutting down the fts optimize thread.
This issue caused by the commit a41d4297.
Fix should check for fts optimize thread shutdown state
before checking fts_optimize_wq.

LATCH_ID_OS_AIO_READ_MUTEX,
LATCH_ID_OS_AIO_WRITE_MUTEX,
LATCH_ID_OS_AIO_LOG_MUTEX,
LATCH_ID_OS_AIO_IBUF_MUTEX,
LATCH_ID_OS_AIO_SYNC_MUTEX: Remove. The tpool is not instrumented.

lock_set_timeout_event(): Remove.

srv_sys_mutex_key, srv_sys_t::mutex, SYNC_THREADS: Remove.

srv_slot_t::suspended: Remove. We only ever assigned this data member
true, so it is redundant.

ib_wqueue_wait(), ib_wqueue_timedwait(): Remove.

os_thread_join(): Remove.

os_thread_create(), os_thread_exit(): Remove redundant parameters.

These were missed in commit 5e62b6a5.

This was missed in commit 30ea63b7.

This has been unused from the very beginning
(mysql/mysql-server@d5e512ae7e37cd1f70c44a3f12205d70b13118ab).

MySQL.com and Percona packages can be root auth_socket only. MariaDB uses unix_socket.
As the root user, as the default Debian maintaince user, needs to
be accessible to run mariadb-upgrade for a start, we make it accessible
again.

ibuf_merge_or_delete_for_page(): Do not attempt to invoke
ibuf_delete_recs() on a page of the change buffer itself.
The caller could already be holding ibuf->index->lock,
and an attempt to acquire it in S mode would hang the release server
or cause an assertion failure in rw_lock_s_lock_func() in a debug
server.

This problem was reproducible on 1 out of 2 runs of the following:
./mtr --no-reorder \
innodb.innodb-page_compression_default \
innodb.innodb-page_compression_snappy \
innodb.innodb-page_compression_zip \
innodb.innodb_wl6326_big innodb.xa_recovery

This was missed in commit 2c252ba9
(MySQL 5.5.42, MariaDB 5.5.42).

This bug happened when the HEAP temporary table used for the derived table
created for a derived handler of a remote engine of the federated type
became full and was converted to an Area table. For this conversion
the tmp_table_param parameter must be always taken from the select_unit
object created for the result of the derived table.

Fix typo.

MDEV-22277 LeakSanitizer: detected memory leaks in mem_heap_create_block_func after attempt to create foreign key

- During online DDL, prepare phase error handler fails to remove
the memory allocated for newly created foreign keys.

Require galera_have_debug_sync.inc and re-record to include new
variables exposed by latest galera library.

This will update galera_3nodes/disabled.def.

Make open_table() fail if sequence should be opened, but it turns out to
be locked view.

MDEV-22330: mysqlbinlog stops with an error Don't know how to handle column type: 255 meta: 4 (0004)

Analysis:
========
"mysqlbinlog -v" option will reconstruct row events and display them as
commented SQL statements. If this option is given twice, the output includes
comments to indicate column data types and some metadata.
`log_event_print_value` is the function reponsible for printing values and
their types. This function doesn't handle GEOMETRY type. Hence the above error
gets printed.

Fix:
===
Add support for GEOMETRY datatype.

The original code was correct. mysql_upgrade calls the mysql client to
talk with MariaDB. It doesn't call itself!

- During insertion of clustered inde, InnoDB does the check for
foreign key constraints. It rebuild the tuple based on foreign
column names when there is no foreign index. While rebuilding,
InnoDB should ignore the dropped columns.

fil_node_t::close_to_free(): Remove some duplicated code that was added in
commit b1ab211d.

Before closing file handles, we really must wait until there are no
pending os_file_flush(). This was missed in
commit b1ab211d (MDEV-15053)
where we changed the following:

    fil_node_close_to_free(): Wait for n_pending==0. Because we no longer
    do an extra lookup of the tablespace between fil_io() and the
    completion of the operation, we must give fil_node_t::complete_io() a
    chance to decrement the counter.

The original code was correct. mysql_upgrade calls the mysql client to
talk with MariaDB. It doesn't call itself!

Part of review of 10.4 code by Sergei.

Other things:

- Changed return type if is_active() from my_bool to bool as this is
  only used by C++ code.

When maria_drop_all_indexes() reset the key files, it didn't flush
the page cache. This confused the cache as there where old key blocks
marked with LSN in it and repair tried to overwrite these with PLAIN
blocks which is not allowed.