Fix reinit_io_cache(WRITE_CACHE) with non-zero seek_offset.
Run encryption.tempfiles with and without binlog checksums.

Timing problem as sometimes table is marked as encrypted but
sometimes we are not sure and table is just marked missing.

Before killing the server, we have to FLUSH TABLES in order to
prevent the corruption of any MyISAM system tables.

PageConverter::adjust_cluster_record(): Instead of writing
the invalid value DB_ROLL_PTR=0, write a value that indicates
a fresh insert, that is, prevents the DB_ROLL_PTR from being
dereferenced in any circumstances.

It can be argued that IMPORT TABLESPACE should actually
update the dict_index_t::trx_id to prevent older transactions
from accessing the table, similar to what I did on table
rebuild in MySQL 5.6.6 in
https://github.com/mysql/mysql-server/commit/03f81a55f221095d397c375afe8a10c8038da339

Use unsigned comparison.

in gcc `-Wno-unsupported-something` will not be an error or even a warning,
so cmake will think the flag is supported. But if there's any other
warning during compilation, for any reason, unknown option will
be a warning too. Or an error when -Werror, even if that "other warning"
would not be an error on itself.

So we need to detect whether `-Wno-unsupported-something` is *really*
supported. Luckily, `-Wunsupported-something` will always fail with an
error.

So, whenever there's a need to detect if -Wno-something is supported,
test -Wsomething instead.

Suppress some messages that are emitted rarely
(when the FIL_PAGE_FILE_FLUSH_LSN of the first page of ibdata1
does not match the latest redo log checkpoint).

Previously, the function could theoretically return an uninitialized
value if the system tablespace contained no data files. It should be
impossible for InnoDB to start up in such scenario.

xtrabackup_init_temp_log(): Remove a redundant variable and limit scope.

The merge omitted some InnoDB and XtraDB conflict resolutions,
most notably, failing to merge the fix of MDEV-12173.

ibuf_merge_or_delete_for_page(), lock_rec_block_validate():
Invoke fil_space_acquire_silent() instead of fil_space_acquire().
This fixes MDEV-12173.

wsrep_debug, wsrep_trx_is_aborting(): Removed unused declarations.

_fil_io(): Remove. Instead, declare default parameters for the XtraDB
fil_io().

buf_read_page_low(): Declare default parameters, and clean up some
callers.

os_aio(): Correct the macro that is defined when !UNIV_PFS_IO.

* use a longer timeout, 10ms is not always enough
* stop waiting as long as the data is read, do not unconditionally
  wait for timeout every time

mysqltest cannot free all memory on exit by design,
so there's no need to check.

mysql frees memory in mysql_end(), so enable memory-leak-on-exit check
only after it was initialized enough to use  mysql_end() - early exits
use my_end().

Do not unwrap view references to keep table info.
(Row-IN subselect does not unwrap items so it does not need fix)

Conflicts:
	storage/innobase/lock/lock0lock.cc
	storage/xtradb/lock/lock0lock.cc
	storage/xtradb/lock/lock0wait.cc
	support-files/mysql.server.sh

Counter for select numbering made stored with the statement (before was global)
So now it does have always accurate value which does not depend on
interruption of statement prepare by errors like lack of table in
a view definition.

only do it in EXTRA_DEBUG builds

don't use internal undocumented OpenSSL functionality

Whenever one copies an IO_CACHE struct, one must remember to call
setup_io_cache, if not, the IO_CACHE's current_pos and end_pos
self-references will point to the previous struct's memory, which
could go out of scope. Commit 90038693
fixes this problem in a more general fashion by removing the
self-references altogether, but for 5.5 we'll keep the old behaviour.

MDEV-15014 Assertion `m_cache_lock_status == LOCKED_NO_WAIT || m_cache_status == DISABLE_REQUEST' failed in Query_cache::free_cache on startup

The assert guards against not-locked or not-requested query cache
disabling. If during startup we disable query cache, we failed to
request disabling.

        The thd->lex->part_info should be kept intact during PS
        execution. Or the second execution gets that modified part_info.
        Let's modify ths->work_part_info instead.

Item_xml_str_func::fix_fields() used a local "String tmp" as a buffer
for args[1]->val_str(). "tmp" was freed at the end of fix_fields(),
while Items created during my_xpath_parse() still pointed to its fragments.

Adding a new member Item_xml_str_func::m_xpath_query and store the result
of args[1]->val_str() into it.

To disable debug instrumentation, save and restore the original value
of the variable DEBUG_DBUG. Assigning -d,... will enable the output of
a lot of unrelated DBUG messages to the server error log.