Two new variables added:
- max_tmp_space_usage : Limits the the temporary space allowance per user
- max_total_tmp_space_usage: Limits the temporary space allowance for
  all users.

New status variables: tmp_space_used & max_tmp_space_used
New field in information_schema.process_list: TMP_SPACE_USED

The temporary space is counted for:
- All SQL level temporary files. This includes files for filesort,
  transaction temporary space, analyze, binlog_stmt_cache etc.
  It does not include engine internal temporary files used for repair,
  alter table, index pre sorting etc.
- All internal on disk temporary tables created as part of resolving a
  SELECT, multi-source update etc.

Special cases:
- When doing a commit, the last flush of the binlog_stmt_cache
  will not cause an error even if the temporary space limit is exceeded.
  This is to avoid giving errors on commit. This means that a user
  can temporary go over the limit with up to binlog_stmt_cache_size.

Noteworthy issue:
- One has to be careful when using small values for max_tmp_space_limit
  together with binary logging and with non transactional tables.
  If a the binary log entry for the query is bigger than
  binlog_stmt_cache_size and one hits the limit of max_tmp_space_limit
  when flushing the entry to disk, the query will abort and the
  binary log will not contain the last changes to the table.
  This will also stop the slave!
  This is also true for all Aria tables as Aria cannot do rollback
  (except in case of crashes)!
  One way to avoid it is to use @@binlog_format=statement for
  queries that updates a lot of rows.

Implementation:
- All writes to temporary files or internal temporary tables, that
  increases the file size, are routed through temp_file_size_cb_func()
  which updates and checks the temp space usage.
- Most of the temporary file monitoring is done inside IO_CACHE.
  Temporary file monitoring is done inside the Aria engine.
- MY_TRACK and MY_TRACK_WITH_LIMIT are new flags for ini_io_cache().
  MY_TRACK means that we track the file usage. TRACK_WITH_LIMIT means
  that we track the file usage and we give an error if the limit is
  breached. This is used to not give an error on commit when
  binlog_stmp_cache is flushed.
- global_tmp_space_used contains the total tmp space used so far.
  This is needed quickly check against max_total_tmp_space_usage.
- Temporary space errors are using EE_LOCAL_TMP_SPACE_FULL and
  handler errors are using HA_ERR_LOCAL_TMP_SPACE_FULL.
  This is needed until we move general errors to it's own error space
  so that they cannot conflict with system error numbers.
- Return value of my_chsize() and mysql_file_chsize() has changed
  so that -1 is returned in the case my_chsize() could not decrease
  the file size (very unlikely and will not happen on modern systems).
  All calls to _chsize() are updated to check for > 0 as the error
  condition.
- At the destruction of THD we check that THD::tmp_file_space == 0
- At server end we check that global_tmp_space_used == 0
- As a precaution against errors in the tmp_space_used code, one can set
  max_tmp_space_usage and max_total_tmp_space_usage to 0 to disable
  the tmp space quota errors.
- truncate_io_cache() function added.
- Aria tables using static or dynamic row length are registered in 8K
  increments to avoid some calls to update_tmp_file_size().

Other things:
- Ensure that all handler errors are registered.  Before, some engine
  errors could be printed as "Unknown error".
- Fixed bug in filesort() that causes a assert if there was an error
  when writing to the temporay file.
- Fixed that compute_window_func() now takes into account write errors.
- In case of parallel replication, rpl_group_info::cleanup_context()
  could call trans_rollback() with thd->error set, which would cause
  an assert. Fixed by resetting the error before calling trans_rollback().
- Fixed bug in subselect3.inc which caused following test to use
  heap tables with low value for max_heap_table_size
- Fixed bug in sql_expression_cache where it did not overflow
  heap table to Aria table.
- Added Max_tmp_disk_space_used to slow query log.
- Fixed some bugs in log_slow_innodb.test

A commit in 10.10 caused it to be always 'No'

Added name of the dll/udf that caused the error.

add old-mode that restores inconsistent legacy behavior for FLUSH STATUS.
It doesn't affect FLUSH { SESSION | GLOBAL } STATUS.

make it easier to add more old-mode values

- FLUSH GLOBAL STATUS now resets most global_status_vars.
  At this stage, this is mainly to be used for testing.
- FLUSH SESSION STATUS added as an alias for FLUSH STATUS.
- FLUSH STATUS does not require any privilege (before required RELOAD).
- FLUSH GLOBAL STATUS requires RELOAD privilege.
- All global status reset moved to FLUSH GLOBAL STATUS.
- Replication semisync status variables are now reset by
  FLUSH GLOBAL STATUS.
- In test cases, the only changes are:
  - Replace FLUSH STATUS with FLUSH GLOBAL STATUS
  - Replace FLUSH STATUS with FLUSH STATUS; FLUSH GLOBAL STATUS.
    This was only done in a few tests where the test was using SHOW STATUS
    for both local and global variables.
- Uptime_since_flush_status is now always provided, independent if
  ENABLED_PROFILING is enabled when compiling MariaDB.
- @@global.Uptime_since_flush_status is reset on FLUSH GLOBAL STATUS
  and @@session.Uptime_since_flush_status is reset on FLUSH SESSION STATUS.
- When connected, @@session.Uptime_since_flush_status is set to 0.

Added SHOW_LONGLONG_NOFLUSH to mark the variables that should not be
flushed.

New variables cleared as part of SHOW STATUS:
- Rpl_semi_sync_master_request_ack
- Rpl_semi_sync_master_get_ac
- Rpl_semi_sync_slave_send_ack
- Slave_skipped_error

Closes #3228

A new GitLab MTR run is added which uses libfaketime to simulate
starting the server and running the test suite in the future.
The job simulates running in two times in the year 2038,
once before the signed 32 bit UNIX limit and once after. This change
helps to ensure that all future changes preserve the ability for the
engine start and function past the year 2038.

All new code of the whole pull request, including one or several
files that are either new files or modified ones, are contributed
under the BSD-new license. I am contributing on behalf of my
employer Amazon Web Services, Inc.

In previous commits, changes were made to use the entire 32 bit
unsigned range in order to support timestamps past 2038 on
64 bit systems. Without changing set_max_time on thr_timer to also
match this new range, the server will crash when attempting to
startup past 2038-01-19. Like the previous commits, this only
applies to 64 bit systems.

All new code of the whole pull request, including one or several
files that are either new files or modified ones, are contributed
under the BSD-new license. I am contributing on behalf of my
employer Amazon Web Services, Inc.

plugins can have unused variables too. If they use a literal "Unused"
string a compiler might or might not merge two identical strings into
one (-fmerge-constants) and depending on that the server will or will
not issue a "variable is ignored" warning.

This will allow us to in the future add better error messages why
an Aria table is crashed.

MDEV-32188 make TIMESTAMP use whole 32-bit unsigned range

- Added --update-history option to mariadb-dump to change 2038
  row_end timestamp to 2106.
- Updated ALTER TABLE ... to convert old row_end timestamps to
  2106 timestamp for tables created before MariaDB 11.4.0.
- Fixed bug in CHECK TABLE where we wrongly suggested to USE REPAIR
  TABLE when ALTER TABLE...FORCE is needed.
- mariadb-check printed table names that where used with REPAIR TABLE but
  did not print table names used with ALTER TABLE or with name repair.
  Fixed by always printing a table that is fixed if --silent is not
  used.
- Added TABLE::vers_fix_old_timestamp() that will change max-timestamp
  for versioned tables when replication from a pre-11.4.0 server.

A few test cases changed. This is caused by:
- CHECK TABLE now prints 'Please do ALTER TABLE... instead of
  'Please do REPAIR TABLE' when there is a problem with the information
  in the .frm file (for example a very old frm file).
- mariadb-check now prints repaired table names.
- mariadb-check also now prints nicer error message in case ALTER TABLE
  is needed to repair a table.

This task is to ensure we have a clear definition and rules of how to
repair or optimize a table.

The rules are:

- REPAIR should be used with tables that are crashed and are
  unreadable (hardware issues with not readable blocks, blocks with
  'unexpected data' etc)
- OPTIMIZE table should be used to optimize the storage layout for the
  table (recover space for delete rows and optimize the index
  structure.
- ALTER TABLE table_name FORCE should be used to rebuild the .frm file
  (the table definition) and the table (with the original table row
  format). If the table is from and older MariaDB/MySQL release with a
  different storage format, it will convert the data to the new
  format. ALTER TABLE ... FORCE is used as part of mariadb-upgrade

Here follows some more background:

The 3 ways to repair a table are:
1) ALTER TABLE table_name FORCE" (not other options).
   As an alias we allow: "ALTER TABLE table_name ENGINE=original_engine"
2) "REPAIR TABLE" (without FORCE)
3) "OPTIMIZE TABLE"

All of the above commands will optimize row space usage (which means that
space will be needed to hold a temporary copy of the table) and
re-generate all indexes. They will also try to replicate the original
table definition as exact as possible.

For ALTER TABLE and "REPAIR TABLE without FORCE", the following will hold:
If the table is from an older MariaDB version and data conversion is
needed (for example for old type HASH columns, MySQL JSON type or new
TIMESTAMP format) "ALTER TABLE table_name FORCE, algorithm=COPY" will be
used.

The differences between the algorithms are
1) Will use the fastest algorithm the engine supports to do a full repair
   of the table (except if data conversions are is needed).
2) Will use the storage engine internal REPAIR facility (MyISAM, Aria).
   If the engine does not support REPAIR then
   "ALTER TABLE FORCE, ALGORITHM=COPY" will be used.
   If there was data incompatibilities (which means that FORCE was used)
   then there will be a warning after REPAIR that ALTER TABLE FORCE is
   still needed.
   The reason for this is that REPAIR may be able to go around data
   errors (wrong incompatible data, crashed or unreadable sectors) that
   ALTER TABLE cannot do.
3) Will use the storage engine internal OPTIMIZE. If engine does not
   support optimize, then "ALTER TABLE FORCE" is used.

The above will ensure that ALTER TABLE FORCE is able to
correct almost any errors in the row or index data.  In case of
corrupted blocks then REPAIR possible followed by ALTER TABLE is needed.
This is important as mariadb-upgrade executes ALTER TABLE table_name
FORCE for any table that must be re-created.

Bugs fixed with InnoDB tables when using ALTER TABLE FORCE:
- No error for INNODB_DEFAULT_ROW_FORMAT=COMPACT even if row length
  would be too wide. (Independent of innodb_strict_mode).
- Tables using symlinks will be symlinked after any of the above commands
  (Independent of the setting of --symbolic-links)

If one specifies an algorithm together with ALTER TABLE FORCE, things
will work as before (except if data conversion is required as then
the COPY algorithm is enforced).

ALTER TABLE .. OPTIMIZE ALL PARTITIONS will work as before.

Other things:
- FORCE argument added to REPAIR to allow one to first run internal
  repair to fix damaged blocks and then follow it with ALTER TABLE.
- REPAIR will not update frm_version if ha_check_for_upgrade() finds
  that table is still incompatible with current version. In this case the
  REPAIR will end with an error.
- REPAIR for storage engines that does not have native repair, like InnoDB,
  is now using ALTER TABLE FORCE.
- REPAIR csv-table USE_FRM now works.
  - It did not work before as CSV tables had extension list in wrong
    order.
- Default error messages length for %M increased from 128 to 256 to not
  cut information from REPAIR.
- Documented HA_ADMIN_XX variables related to repair.
- Added HA_ADMIN_NEEDS_DATA_CONVERSION to signal that we have to
  do data conversions when converting the table (and thus ALTER TABLE
  copy algorithm is needed).
- Fixed typo in error message (caused test changes).

Remove alter_algorithm but keep the variable as no-op (with a warning).

The reasons for removing alter_algorithm are:
- alter_algorithm was introduced as a replacement for the
  old_alter_table that was used to force the usage of the original
  alter table algorithm (copy) in the cases where the new alter
  algorithm did not work. The new option was added as a way to force
  the usage of a specific algorithm when it should instead have made
  it possible to disable algorithms that would not work for some
  reason.
- alter_algorithm introduced some cases where ALTER TABLE would not
  work without specifying the ALGORITHM=XXX option together with
  ALTER TABLE.
- Having different values of alter_algorithm on master and slave could
  cause slave to stop unexpectedly.
- ALTER TABLE FORCE, as used by mariadb-upgrade, would not always work
  if alter_algorithm was set for the server.
- As part of the MDEV-33449 "improving repair of tables" it become
  clear that alter- algorithm made it harder to provide a better and
  more consistent ALTER TABLE FORCE and REPAIR TABLE and it would be
  better to remove it.

This enasures that the 'variables that only exists for compatibility'
are always kept as its default value.

Based on an idea from Sergei Golubchik

Also fixed that all unused variables are using the same variable comment.
The warning will be tested with the next commit that deprecates the
variable alter_algorithm.

MDEV-32188 make TIMESTAMP use whole 32-bit unsigned range

This was done by changing DTVAL to use longlong to internally store
the date/timestamp instead of an int.

I had to preserve the old binary representation used for dates in
TABLE_TYPE=BIN. One consequence is that TABLE_TYPE=BIN cannot support
the full date bit range.

MDEV-32188 make TIMESTAMP use whole 32-bit unsigned range

- Changed usage of timeval to my_timeval as the timeval parts on windows
  are 32-bit long, which causes some compiler issues on windows.

MDEV-32188 make TIMESTAMP use whole 32-bit unsigned range

This is done by changing my_time_t from long to unsigned long.
The effect of this is that on windows compling old clients may
get warnings of if they compare my_time_t with as signed variable.

Other things
- Removed my_time_t from include/*.pp files as it is different on windows
  and linux.
- Changed do_abi_check.cmake to first print abi_check and then the
  conflicting file (this makes it easier to find the cause of the error).

This patch extends the timestamp from
2038-01-19 03:14:07.999999 to 2106-02-07 06:28:15.999999
for 64 bit hardware and OS where 'long' is 64 bits.
This is true for 64 bit Linux but not for Windows.

This is done by treating the 32 bit stored int as unsigned instead of
signed.  This is safe as MariaDB has never accepted dates before the epoch
(1970).
The benefit of this approach that for normal timestamp the storage is
compatible with earlier version.

However for tables using system versioning we before stored a
timestamp with the year 2038 as the 'max timestamp', which is used to
detect current values.  This patch stores the new 2106 year max value
as the max timestamp. This means that old tables using system
versioning needs to be updated with mariadb-upgrade when moving them
to 11.4. That will be done in a separate commit.

- Slave_IO thread time is now reset between reading events. Before
  this commit Slave_IO always showed "Waiting for master to send
  event" and the time was from SLAVE START. Now it shows time since
  reading last event.

This is to make it easier to understand why master_pos_wait() fails in mtr.

Fixed that no tables from 'mysql' schema are included in userstat.
A beneif of this is that the server is not reading statistics tables
if mysql.proc or other tables in mysql is accessed.

Other changes:
- Do not collect index statistics for system tables like index_stats
  table_stats, performance_schema, information_schema etc as the user
  has no control of these and the generate noise in the statistics.

what is done in the plugin - stays in the plugin

and adjust the copyright year

This is to update the plugin to be compatible with Percona's
query_response_time plugin, with some additions.
Some of the tests are taken from Percona server.

- Added plugins QUERY_RESPONSE_TIME_READ, QUERY_RESPONSE_TIME_WRITE and
  QUERY_RESPONSE_TIME_READ_WRITE.
- Added option query_response_time_session_stats, with possible values
  GLOBAL, ON or OFF, to the query_response_time plugin.

Notes:
- All modules are dependent on QUERY_RESPONSE_READ_TIME. This must always
  be enabled if any of the other modules are used.
  This will be auto-enabled in the near future.
- Accounting are done per statement. Stored functions are regarded
  as part of the original statement.
- For stored procedures the accounting are done per statement executed
  in the stored procedure. CALL will not be accounted because of this.
- FLUSH commands will not be accounted for. This is to ensure that
  FLUSH QUERY_RESPONSE_TIME is not part of the statistics.
  (This helps when testing with mtr and otherwise).
- FLUSH QUERY_RESPONSE_TIME_READ and FLUSH QUERY_RESPONSE_TIME_READ
  only resets the corresponding status.
- FLUSH QUERY_RESPONSE_TIME and FLUSH QUERY_RESPONSE_TIME_READ_WRITE or
  changing the value of query_response_time_range_base followed by
  any FLUSH of QUERY_RESPOSNSE_TIME resets all status.

Various help message improvements:
* MySQL->MariaDB, mysqld->mariadbd, "mysqld daemon" -> "mariadbd process"
* typos
* don't specify defaults directly in the help message
* don't say that an option is deprecated, mark is as such
* missing spaces in the middle of the text
etc

it was a no-op, plugin variables don't have dashes

* use new deprecated printer for all deprecated server options
* restore alphabetic option sorting order
* move deprecated printer from mysqld.cc to my_getopt.c
* in --help print deprecation message at the end of the option help
* move 'ALL' help text where it belongs - to other SET options, and
  with a correct indentation.
* consistently end all or none command-line option help strings
  with a dot - my_print_help() needs that.
  It's about 50/50 now, so let's do none, less line wraps in --help
* remove trailing spaces from command-line option help strings