Problem:
=========
One of the purge thread access the corrupted page and tries to remove from
LRU list. In the mean time, other purge threads are waiting for same page
in buf_wait_for_read(). Assertion(buf_fix_count == 0) fails for the
purge thread which tries to remove the page from LRU list.

Solution:
========
- Set the page id as FIL_NULL to indicate the page is corrupted before
removing the block from LRU list. Acquire hash lock for the particular
page id and wait for the other threads to release buf_fix_count
for the block.

- Added the error check for btr_cur_open() in row_search_on_row_ref().

Before killing the server, ensure that the incomplete state of
the transaction will be made durable and will be applied and
rolled back on recovery, so that each time, roughly the same
amount of work will be done.

Remove DML statements after the recovery, and execute
CHECK TABLE instead.

Remove the test, because it easily fails with a result difference.
Analysis by Thirunarayanan Balathandayuthapani:

By default, innodb_encrypt_tables=0.
1) Test case creates 100 tables in innodb_encrypt_1.
2) creates another 100 unencrypted tables (encryption=off) in innodb_encrypt_2
3) creates another 100 encrypted tables (encryption=on) in innodb_encrypt_3
4) enabling innodb_encrypt_tables=1 and checking that only
100 encrypted tables exist. (already we have 100 in dictionary)
5) opening all tables again (no idea why)
6) After that, set innodb_encrypt_tables=0 and wait for 100 tables
to be decrypted (already we have 100 unencrypted tables)
7) dropping all databases

Sporadic failure happens because after step 4, it could encrypt the
normal table too, because innodb_encryption_threads=4.

This test was added in MDEV-9931, which was about InnoDB startup being
slow due to all .ibd files being opened. There have been a number of
later fixes to this problem. Currently the latest one is
commit cad56fba, in which some tests
(in particular the test innodb.alter_kill) could fail if all InnoDB
.ibd files are read during startup. That could make this test redundant.

Let us remove the test, because it is big, slow, unreliable, and
does not seem to reliably catch the problem that all files are being
read on InnoDB startup.

GCC 9.1.1 noticed that sd_notifyf() was always being invoked with
str=NULL argument for "%s". This code was added in
commit 2e814d47
but not mentioned in the commit comment.

The STATUS messages for systemd matter during startup and shutdown,
and should not be emitted during normal operation.

ib_senderrf(): Remove the potentially harmful sd_notifyf() calls.

innodb_locks_unsafe_for_binlog variabe removed from wsrep_info test configuration and
recommendation to use this variable in README-wsrep was removed as well

Also relates to issue: MDEV-19544

This patch fixes 10.2 issue reported in MDEV-16467 by partial backport of
c2118a08. Specifically "Remove not needed LOCK_thread_count from
thd_get_error_context_description()".

MDEV-16866 InnoDB fails to start upon crash recovery with "[ERROR] InnoDB: Redo log crypto: failed to decrypt log block"

- Post-push fix to change the copyright of both xtradb and innodb file.

MDEV-16866 InnoDB fails to start upon crash recovery with "[ERROR] InnoDB: Redo log crypto: failed to decrypt log block"

- If InnoDB encounters garbage or incomplete written log block during
recovery then don't throw the error. Treat it as end of the log.
- This kind of incomplete or empty block can be result of killing
InnoDB when writing the redo log.

Remove unneeded select to provider name. Provider can have different
names and can be located on different directory on different
environments.

Some I/O functions and macros that are declared in os0file.h used to
return a Boolean status code (nonzero on success). In MySQL 5.7, they
were changed to return dberr_t instead. Alas, in MariaDB Server 10.2,
some uses of functions were not adjusted to the changed return value.

Until MDEV-19231, the valid values of dberr_t were always nonzero.
This means that some code that was incorrectly checking for a zero
return value from the functions would never detect a failure.

After MDEV-19231, some tests for ALTER ONLINE TABLE would fail with
cmake -DPLUGIN_PERFSCHEMA=NO. It turned out that the wrappers
pfs_os_file_read_no_error_handling_int_fd_func() and
pfs_os_file_write_int_fd_func() were wrongly returning
bool instead of dberr_t. Also the callers of these functions were
wrongly expecting bool (nonzero on success) instead of dberr_t.

This mistake had been made when the addition of these functions was
merged from MySQL 5.6.36 and 5.7.18 into MariaDB Server 10.2.7.

This fix also reverts commit 40becbc3
which attempted to work around the problem.

Make it visible

Those two may work incorrectly together. Namely, ASAN may produce
false positives or false negatives. For details see
https://github.com/google/sanitizers/wiki/AddressSanitizer#faq

Make SECURITY_HARDENED disabled by default if WITH_ASAN=ON

Based on contribution by Eugene Kosov.

option values now have to be edited in-place,
instead of replacing an option with another one
that has the same name but a new value.

- --disable-plugin-load or --skip-plugin-load will now reset plugin load
  list. Needed for future changes to mtr tests

- multiple usage of plugin-load-add and optimizer-switch are now included
  in generated config files

Problem:
=======
fil_iterate() writes imported tablespace page0 as it is to discarded
tablespace. Space id wasn't even changed. While opening the tablespace,
tablespace fails with space id mismatch error.

Fix:
====
fil_iterate() copies the page0 with discarded space id to imported
tablespace.

messages

Force LANG=C for MY_CHECK_{C,CXX}_COMPILER_FLAG

fix MDEV-18750: failed to flashback large-size binlog file

fix mysqlbinlog flashback failure caused by reading io_cache without MY_FULL_IO flag

fix MDEV-18750: mysqlbinlog flashback failure on large binlog

- Use corrupt page id instead of whole block after releasing it from
LRU list.

MDEV-18015: Assertion `global_status_var.global_memory_used == 0' failed when using UDF , window functions and views

Adding destructor for Group_bound_tracker to free Cached_item_str.
The Cached_item for window functions are allocated on THD:mem_root
but the Cached_item_str has value of type string which is allocated on
the heap, so we need to call free() for it

os_file_write_func() and os_file_read_no_error_handling_func() returned
different result values depending on if UNIV_PFS_IO was defined or not.

Other things:
- Added some comments about return values for some functions

Wrong compiler warning from GCC:
‘snprintf’ output 2 or more bytes (assuming 4001)
into a destination of size 4000

- --default-character-set can now be disabled in mysqldump
- --skip-resolve can be be disabled in mysqld
- mysql_client_test now resets global variables it changes
- mtr couldn't handle [mysqldump] in config files (wrong regexp used)

Do not use TARGET_LINK_LIBRARIES(mysys mysys_ssl),
this means that mysys_ssl is linked to practically everything.

The issue is that two MARIA_HA instances shares the same MARIA_STATUS_INFO
object during UNION execution, so the second MARIA_HA instance state pointer
MARIA_HA::state points to the MARIA_HA::state_save of the first MARIA instance.

This happens in
thr_multi_lock(...) {
...
	for (first_lock=data, pos= data+1 ; pos < end ; pos++)
	{
...
		if (pos[0]->lock == pos[-1]->lock && pos[0]->lock->copy_status)
			(pos[0]->lock->copy_status)((*pos)->status_param,
																	(*first_lock)->status_param);
...
	}
...
}

Usually the state is restored from ha_maria::external_lock(...):

\#0  _ma_update_status (param=0x6290000e6270) at ./storage/maria/ma_state.c:309
\#1  0x00005555577ccb15 in _ma_update_status_with_lock (info=0x6290000e6270) at ./storage/maria/ma_state.c:361
\#2  0x00005555577c7dcc in maria_lock_database (info=0x6290000e6270, lock_type=2) at ./storage/maria/ma_locking.c:66
\#3  0x0000555557802ccd in ha_maria::external_lock (this=0x61d0001b1308, thd=0x62a000048270, lock_type=2) at ./storage/maria/ha_maria.cc:2727

But _ma_update_status() does not take into account the case when
MARIA_HA::status points to the MARIA_HA::state_save of the other MARIA_HA
instance.

The fix is to restore MARIA_HA::state in ha_maria::external_lock() after
maria_lock_database() call for transactional tables.

Reverted incorrect change introduced by 548d03d7.

As result is char**, third qsort() parameter must be sizeof(char*).
Not sizeof(result[0] + 2), which is same as sizeof(result[0]).
Not even sizeof(result[0]) + 2, which would cause invalid memory access.

Proper sorting is responsibility of logfilenamecompare() callback.

Removed #! sequence from non-executable script.