A side effect of the MDEV-24589 bug fix is that if
FLUSH TABLE...FOR EXPORT is initiated before the history of an
earlier DROP INDEX operation has been purged, then the data file
will contain allocated pages that belonged to the dropped indexes.
These pages would never be freed after a subsequent IMPORT TABLESPACE.

We will work around this regression by making IMPORT TABLESPACE
tolerate pages that refer to an unknown index.

HAVE_valgrind_or_MSAN to HAVE_valgrind was incorrect in
af784385.

In my_valgrind.h when clang exists (hence no __has_feature(memory_sanitizer),
and -DWITH_VALGRIND=1, but without memcheck.h, we end up with a MEM_CHECK_DEFINED
being empty.

If we are also doing a CMAKE_BUILD_TYPE=Debug this results a number of
[-Werror,-Wunused-variable] errors because MEM_CHECK_DEFINED is empty.
With MEM_CHECK_DEFINED empty, there becomes no uses of this of the
fixed field and innodb variables in this patch.

So we stop using HAVE_valgrind as catchall and use the name
HAVE_CHECK_MEM to indicate that a CHECK_MEM_DEFINED function exists.

Reviewer: Monty

Corrects: af784385

Mostly a refactoring. Also, debug functions were added for ease of life while debugging

- use FIND_PACKAGE(LIBAIO) to find libaio
- Use standard CMake conventions in Find{PMEM,URING}.cmake
- Drop the LIB from LIB{PMEM,URING}_{INCLUDE_DIR,LIBRARIES}
  It is cleaner, and consistent with how other packages are handled in CMake.
  e.g successful FIND_PACKAGE(PMEM) now sets PMEM_FOUND, PMEM_LIBRARIES,
  PMEM_INCLUDE_DIR, not  LIBPMEM_{FOUND,LIBRARIES,INCLUDE_DIR}.
- Decrease the output. use FIND_PACKAGE with QUIET argument.
- for Linux packages, either liburing, or libaio is required
  If liburing is installed, libaio does not need to be present   .
  Use FIND_PACKAGE([LIBAIO|URING] REQUIRED) if either library is required.

row_upd_clust_step(): Remove the "trigger" on DELETE SYS_INDEXES
that would invoke dict_drop_index_tree(). Let us do it on purge.

row_purge_remove_clust_if_poss_low(): Invoke
dict_drop_index_tree() when purging a delete-marked SYS_INDEXES record.

dict_table_open_on_index_id(): Remove. This function was used by
the background scrubbing, which was removed in
commit a5584b13.

When we are testing under valgrind, we should be
testing the actual code path used in production code.

This optimization of using shutdown did, in pre-2009,
help purify shutdown quickly. In
b125770a this magicly
equated to valgrind, in 2009.

Reviewer: Monty

Currently for the server, we only check if $MYSQL_HOME is set. Added a check
if $MARIADB_HOME is set and try to read the configuration file from this
directory. If $MARIADB_HOME is NULL, only then check $MYSQL_HOME.

Found by running valgrind on mtr tests

Reseting -> Resetting
Unknow -> Unknown
capabilites -> capabilities
choosen -> chosen
direcory -> directory
informations -> information
openned -> opened
refered -> referred
to access -> one to access
missmatch -> mismatch
succesfully -> successfully
dont -> don't

Update test results: rocksdb.type_blob_indexes, rocksdb.type_text_indexes

- Removed not used variables
- Added /* fall through */ to switches
- Removed not used static variable 'slash' from header file
- Removed test of fp->field_length >= 0 as it is always true

Problem was that listen_sockets where not properly protected.
Fixed by adding LOCK_start_thread around closing socket loop.

Other things:
- Removed not necessary test in close_socket(). With the current code
  'sock' can never be INVALID_SOCKET.

Main reason for this was there was a crash in shutdown of the server
in binlog_encryption.encryption_combo-mix and some other tests because
something in listen_sockets where not initialized. Changing to
Dynamic_array caused things to work.
Other reason for removing std::vector was that it is harder to debug,
and not integrated with DBUG, safemalloc, valgrind or memory
calculation and cause code explosions (extra code generated for each
std::vector type used).

Other things:
- Added size() function to Dynamic_array()

In the case of a crash directly after a creation of an Aria table,
Aria recovery would think that the table was from another system and
require a repair of the table and inform that the table is 'zerofilled".
This would cause no harm, but was confusing to see when testing atomic
alter table.

Fixed by logging the create transaction id to the log.

Other things:
- Added "show table status from sys" to maria_empy_logs. This ensures one
  does not get any zerofill warnings when sys/sys_config is used by other
  tests.
- aria_chk --describe now prints a warning if the table was moved from
  another system.
- Logging of truncate (maria_delete_all_rows) is changed to use the
  current trid for the create table.
  This is to ensure that we do not run into the same problem with truncate.
- Changed back sys_config table to Aria as this patch should fix the
  "zerofill" problem in buildbot.
- Added scripts/mysql_sys_schema.sql to .gitignore

The new default values WITH_URING:BOOL=OFF, WITH_PMEM:BOOL=OFF imply
that the dependencies are optional.
An explicit request WITH_URING=ON or WITH_PMEM=ON will cause the
build to fail if the requested dependencies are not available.

Last, to prevent a feature to be built in even though the built-time
dependencies are available, the following can be used:

cmake -DCMAKE_DISABLE_FIND_PACKAGE_URING=1
cmake -DCMAKE_DISABLE_FIND_PACKAGE_PMEM=1

This cleanup was suggested by Vladislav Vaintroub.

In commit 412533b4 (MDEV-18582),
one of the counters that was ported from XtraDB is useless.
Innodb_buffered_aio_submitted would be 0 or 1, depending on whether
is_linux_native_aio_supported() was executed to the point where
it would be incremented.

Let us remove this counter, because it has no practical value.
Even if its value were 1, io_setup() can still fail and we may
end up with innodb_use_native_aio=0.

In this platform, it s better not to rely on optional proc filesystem presence.
 Using native API to retrieve binary absolute path instead.

Fix for out-of-tree builds.

mysql_sys_schema.sql is a CMAKE_CURRENT_BINARY_DIR file so
use the buildpkgdatadir.

Fix by adding sys schema to cat_sql()

Print the build_equal_items() step for ON expression processing

Print the conditions for WHERE, HAVING, and ON.

This partially reverts 66106130