If libpcre2 (10.x) is not defined and only the older libpcre3 (8.x)
would be available, the build would attempt to download it from the
Internet, violating many build environment restrictions.

Commit b6b69806 attempted to fix
MDEV-21942 but was incomplete, and after in CI systems started
failing since the .travis.yml update was missing.

Thanks to MDEV-15058, there is only one InnoDB buffer pool.
Allocating buf_pool statically removes one level of pointer indirection
and makes code more readable, and removes the awkward initialization of
some buf_pool members.

While doing this, we will also declare some buf_pool_t data members
private and replace some functions with member functions. This is
mostly affecting buffer pool resizing.

This is not aiming to be a complete rewrite of buf_pool_t to
a proper class. Most of the buffer pool interface, such as
buf_page_get_gen(), will remain in the C programming style
for now.

buf_pool_t::withdrawing: Replaces buf_pool_withdrawing.
buf_pool_t::withdraw_clock_: Replaces buf_withdraw_clock.

buf_pool_t::create(): Repalces buf_pool_init().
buf_pool_t::close(): Replaces buf_pool_free().

buf_bool_t::will_be_withdrawn(): Replaces buf_block_will_be_withdrawn(),
buf_frame_will_be_withdrawn().

buf_pool_t::clear_hash_index(): Replaces buf_pool_clear_hash_index().
buf_pool_t::get_n_pages(): Replaces buf_pool_get_n_pages().
buf_pool_t::validate(): Replaces buf_validate().
buf_pool_t::print(): Replaces buf_print().
buf_pool_t::block_from_ahi(): Replaces buf_block_from_ahi().
buf_pool_t::is_block_field(): Replaces buf_pointer_is_block_field().
buf_pool_t::is_block_mutex(): Replaces buf_pool_is_block_mutex().
buf_pool_t::is_block_lock(): Replaces buf_pool_is_block_lock().
buf_pool_t::is_obsolete(): Replaces buf_pool_is_obsolete().
buf_pool_t::io_buf: Make default-constructible.
buf_pool_t::io_buf::create(): Delayed 'constructor'
buf_pool_t::io_buf::close(): Early 'destructor'

HazardPointer: Make default-constructible. Define all member functions
inline, also for derived classes.

MDEV-21975 Add BINLOG REPLAY privilege and bind new privileges to gtid_seq_no, preudo_thread_id, server_id, gtid_domain_id

MDEV-21971 Bind BINLOG ADMIN to binlog_annotate_row_events and binlog_row_image global and session variables

MDEV-21969 Bind REPLICATION SLAVE ADMIN to relay_log_*, sync_master_info, sync_relay_log, sync_relay_log_info

Added options:
--datadir
--ignore-control-file
--require-control-file

- Improved error messages if open fails
- If control file can't be found/opened, assume that all rows in the
  tables are commited.

Problem was that replace_dynstr_append_mem() assumed strings are
null terminated which is not always the case.

Simplifying definitions on Sys_var_charptr*:

- Removing sys_var::is_os_charset
- Adding a new class Sys_var_charptr_fscs, to handle system
  variables with character_set_filesystem.

           'index_merge_sort_union=off'

When index_merge_sort_union is set to 'off' and  index_merge_union is set
to 'on' then any evaluated index merge scan must consist only of ROR scans.
The cheapest out of such index merges must be chosen. This index merge
might not be the cheapest index merge.

This was to remove a performance regression between 10.3 and 10.4
In 10.5 we will have a better implementation of records_in_range
that will enable us to get more statistics.
This change was not done in 10.4 because the 10.5 will be part of
a larger change that is not suitable for the GA 10.4 version

Other things:
- Changed default handler block_size to 8192 to fix things statistics
  for engines that doesn't set the block size.
- Fixed a bug in spider when using multiple part const ranges
  (Patch from Kentoku)

Move function ut_crc32_swap_byteorder to a non-x86 #ifdef area.

As its only used in BIGENDIAN, use #ifdefs around
ut_crc32_swap_byteorder.

Travis CI and Debian both include s390x in builds/test, which is big endian.

Fixes commit: 1312b4eb

It did not work, eventhough the default for Windows was changed to 1
for the corresponding system variable.
This be because  test_flags was zeroed mysql_init_variables.

The patch fixes this glitch.

log_write_buf(): Remove the unused variable write_header.
The dependent code was removed in
commit 0c2365c4.
That was dead or unnecessary code at least ever since
commit 9ef2d29f
removed the support for innodb_log_files_in_group>1.

This should fix the following failure:

+ Warnings:
+ Warning       1639    debug sync point wait timed out

mi_records_in_range(): Because HA_POS_ERROR cannot be accurately
represented in double (it will be off by one), add an explicit
cast to silence the warning.

log_t::has_encryption_key_rotation(): checks whether
key rotation is supported.

In a subsequent redo log format version, this key rotation
may be broken again.

Write log header just ones when file is created, instead of
writing to it on every log file wrap around.

log_t::file::write_header_durable(): this one writes to log header

log_write_buf(): this one stops writing to log header

move statistics modification into one place

restore check for client charset_info == NULL, which was previously
removed in MDEV-8844

that by a (un)lucky coincidence did not prevent 8fd654ce
from working properly

when selecting from perfschema, filter out statements
used by the test istself in wait_condition.inc, because they,
by design, can be repeated unpredictable number of times.