log_buf_pool_get_oldest_modification(): Acquire
log_sys_t::flush_order_mutex in order to prevent a race condition
that was introduced in
commit 1a6f708e (MDEV-15058).

Before that change, log_buf_pool_get_oldest_modification()
was protected by both log_sys.mutex and log_sys.flush_order_mutex
like it was supposed to be ever since
commit a52c4820 (MySQL 5.5.10).

buf_pool_t::get_oldest_modification(): Replaces
buf_pool_get_oldest_modification(), to emphasize that
log_sys.flush_order_mutex must be acquired by the caller if needed.

log_close(): Invoke log_buf_pool_get_oldest_modification()
in order to ensure a clean shutdown.

The scenario of the race condition is as follows:

1. The buffer pool is clean (no writes are pending).
2. mtr_add_dirtied_pages_to_flush_list() releases log_sys.mutex.
3. log_buf_pool_get_oldest_modification() observes that the
buffer pool is clean and returns log_sys.lsn.
4. log_checkpoint() completes, writing a wrong checkpoint header
according to which everything up to log_sys.lsn was clean.
5. mtr_add_dirtied_pages_to_flush_list() completes the execution
of mtr_memo_note_modifications(), releases the page latches and
the flush_order_mutex.
6. On a subsequent log_checkpoint(), the assertion could fail
if the page modifications had not been flushed yet.

The failing assertion (which is valid) was added in MySQL 5.7
mysql/mysql-server@5c6c6ec69336369487dfc080a6980089b4e1a3c2
and merged to MariaDB Server 10.2.2 in
commit fec844ac.

exporting data from the server needs MYSQL_PLUGIN_IMPORT.

For character sets and collation where character to weight mapping > 1,
there we need to make sure while creating a sort key,
a temporary buffer is created to store the value of the item by val_str function
and then copy that value back to the sort buffer.
In this case when using a priority queue Sort_param::tmp_buffer was not allocated.

Minor refactoring:
Changed Sort_param::tmp_buffer from char* to String

MENT-458 MTR Big test "spider/bugfix.sql_mode_mariadb & myself" are both failing on Azure MTR pipeline

Support the dash number of MariaDB versions by Spider's tests

Support the dash number of MariaDB versions by Spider's install sequence

Item_sum_sp did not override val_native(). So the reported script
crashed in the default implementation in Item::val_native() on DBUG_ASSERT().

Implementing a correct Item_sum_sp::val_native().

Existing implementation used my_checksum (from mysys)
for calculating table checksum and binlog checksum.

This implementation was optimized for powerpc only and lacked
SIMD implementation for x86 (using clmul) and ARM
(using ACLE) instead used zlib-crc32.

mariabackup had its own copy of the crc32 implementation
using hardware optimized implementation only for x86 and lagged
hardware based implementation for powerpc and ARM.

Patch helps unifies all such calls and help aggregate all of them
using an unified interface my_checksum().

Said unification also enables hardware optimized calls for all
architecture viz. x86, ARM, POWERPC.
Default always fallback to zlib crc32.

Thanks to Daniel Black for reviewing, fixing and testing
PowerPC changes. Thanks to Marko and Daniel for early code feedback.

Disallowing EXTRACT(xxx FROM inet6arg) as fix time.
Adding a new method Type_handler::can_return_extract_source().

The opt_for_user subrule was incorrectly scanned before sp_create_assignment_lex(),
so the user name and the host were created on a wrong memory root.

- Reoganizing the grammar to make sure that sp_create_assignment_lex()
  is called immediately after PASSWORD_SYM is scanned, so all attributes
  are then allocated on its memory root.

- Moving the semantic code as methods to LEX, so the grammar looks as simple as possible.

- Changing text_or_password to be of the data type USER_AUTH*.
  As a side effect, the LEX::definer member is now not used when processing
  the SET PASSWORD statement. Everything is done using Bison's stack.

The bug sas introduced by this commit:
commit bf5a144e

Less error prone, stricter type control.

This couldn't cause any bugs as ptr was zero terminated, but still better
to have the length correct.

This change also affects information_schema.tables

The create table option "transactional=0 | 1" is now always shown for
storage engines that supports both transactional/crash safe tables and
non transactional tables.

Before this patch the transactional=... option was only shown if the user
specified transactional=... in the CREATE TABLE or ALTER TABLE statement.
The reason for the change was to be able to make it easy to know if an Aria
table is transactional or not.

A crash was observed where dict_acquire_mdl_shared<trylock=false>
would invoke memcpy() with an apparently uninitialized tbl_len.

dict_table_t::parse_name(): Remove an unnecessary tbl_len--
operation. (This should be mostly non-functional cleanup.)

dict_acquire_mdl_shared(): If the second dict_table_t::parse_name()
returns false, terminate the loop just like we would do on the
first invocation.

MDEV-22746: Assertion `(&(&pagecache->cache_lock)->m_mutex)->count > 0 && pthread_equal(pthread_self(), (&(&pagecache->cache_lock)->m_mutex)->thread)' failed in dec_counter_for_resize_op

Removed second attempt to decrease counter

(The table already existed in the storage engine)

Wrong algorithm of closing partitions on error doesn't close last
partition.

commit d09aec7a (MDEV-19940)
caused a regression. We made wait_lock_get_heap_no() return
uint16_t instead of ulint, and we mostly replaced the previous
magic value ULINT_UNDEFINED with 0. But, we failed to adjust
some assertions. Furthermore, 0 is a valid although rare value
for record locks. (Record locks can be temporarily stored on
page infimum in some operations that involve multiple leaf pages.)

Let us use 0xFFFF as the magic value. Valid heap numbers
are limited to less than 9362 = innodb_page_size/(5+1+1)
when using a minimal 1-byte PRIMARY KEY and a
secondary index on a NULL or '' column.

when checking for free port, use the same logic (IPv6 socket address
/ dual socket), like the server would.

Previous solution for testing whether port is free was trying to bind
IPv4 socket on INADDR_ANY.

This not work now on some reason, that attempt succeeds, even if there is
an existing IPv6-dual socket listening on 0.0.0.0:3306

It works, but irritates people who look into the log and see
traces of 32bit custom action server.

In the merge 9e6e4355 we replaced
direct use of std::atomic with a wrapper class, so that
dict_index_t::lock will support the default assignment operator.

As part of that change, one occurrence of std::memory_order_release
was accidentally replaced with std::memory_order_relaxed.

Thanks to Sergey Vojtovich for noticing this.

Wrong condition for corner values.

Respect system fields in NO_ZERO_DATE mode.

This is the subject for refactoring in MDEV-19597

Conflict resolution from 7d5223310789f967106d86ce193ef31b315ecff0

The constructor of Lex_ident_sys returns LEX_CSTRING(NULL,0) if character set
conversion goes wrong, and raises the "wrong character string" error in
the diagnostics area.

The code in sql_yacc.yy did not check Lex_ident_sys::ptr against NULL,
so the execution entered functions that did not expect NULL (and crashed).

Fixing the code to do MYSQL_YYABORT if Lex_ident_sys::ptr is NULL
after constructing.

Respect system fields in NO_ZERO_DATE mode.

This is the subject for refactoring in MDEV-19597