This version is not optimized yet. It could have bugs because I didn't
check it with unit tests. Also, std::char_traits are not really supported.
So, now it's not possible to create f.ex. a case insensitive string_view.

fil_path_to_space_name(): renamed, moved to another file
and refactored to use string_view

This form of corruption was only reproduced on MariaDB 10.5.4
after the MDEV-22867 fix was applied in
commit 43120009.

While we do not know how to reproduce this corruption in
MariaDB 10.4, we are applying the code fix without a test case.

btr_cur_pessimistic_update(): Invoke btr_set_instant() if needed.

The auth_pam_tool that is executed from pam_auth() can be still
not finished by the time we do the waitpid() there.
As we use WNOHANG option for the waitpid(), it didn't wait and
left the zombie process. So let's do the loop of waitpid() with the
limited number of sleeps.

In mi_check_index_tuple(), when rowid filter check returns
CHECK_OUT_OF_RANGE, set info->lastpos= HA_OFFSET_ERROR, like
it is done above for the ICP check.

Check if we really need the mariadb.sys user

commit 48493132 was a necessary
fix for the buffer pool resizing tests in 10.5 in
AddressSanitizer. However, that change would break the tests
innodb.innodb_buffer_pool_resize and
innodb.innodb_buffer_pool_resize_with_chunks
when run in MemorySanitizer, or presumably in Valgrind as well.
(Those tests run "forever" in Valgrind.)

buf_pool_resize(): Cancel the effect of MEM_NOACCESS() in Valgrind
and ASAN. In MSAN, MEM_NOACCESS() is a no-op, and hence we must do
nothing special here.

MEM_MAKE_ADDRESSABLE() would declare the memory contents undefined.
In this particular case, we must actually declare the contents
defined for Valgrind.

In AddressSanitizer, we only want memory poisoning to happen
in connection with custom memory allocation or freeing.

The primary use of MEM_UNDEFINED is for declaring memory uninitialized
in Valgrind or MemorySanitizer. We do not want MEM_UNDEFINED to
have the unwanted side effect that AddressSanitizer would no longer
be able to complain about accessing unallocated memory.

MEM_UNDEFINED(): Define as no-op for AddressSanitizer.

MEM_MAKE_ADDRESSABLE(): Define as MEM_UNDEFINED() or
ASAN_UNPOISON_MEMORY_REGION().

MEM_CHECK_ADDRESSABLE(): Wrap also __asan_region_is_poisoned().

- Some of the bug fixes are backports from 10.5!
- The fix in innobase/fil/fil0fil.cc is just a backport to get less
  error messages in mysqld.1.err when running with valgrind.
- Renamed HAVE_valgrind_or_MSAN to HAVE_valgrind

When using field_conv(), which is called in case of field1=field2 copy in
fill_records(), full varstring's was copied, including unitialized bytes.
This caused valgrind to compilain about usage of unitialized bytes when
using Aria static length records.
Fixed by not using memcpy when copying varstrings but instead just copy
the real bytes.

- Removed not needed bzero in void TABLE::initialize_quick_structures().
- Replaced bzero with TRASH_ALLOC() to have this change verfied with
  memory checkers
- Added missing table->quick_keys.is_set in table_cond_selectivity()

galera_toi_truncate test launches a long term INSERT statement in node 2,
and then submits an offending TRUNCATE through node 1. The idea is that
the replicated TRUNCATE will conflict with INSERT in node 2, and force
the INSERT to abort.

The test first issues --send INSERT in node 2, and then switches to node 1
to launch --send TRUNCATE. As the INSERT is launched asynchronously by --send,
it may happen that INSERT has not yet started to process, before the TRUNCATE
is replicated. The net effect may be that TRUCATE processes to completion in node 2,
and only after that INSERT starts to execute. As the INSERT is very long query,
it will last longer than mtr test suite max test time, the test will fail for timeout.

The fix in this commit uses another connection in node 2, to wait until the INSERT
has started to process in node 2. TRUNCATE in node 1, will be submitted in node 1
after this wait condition.

This reverts commit e0793d38.

In idiomatic C++, accessor functions should not discard qualifiers.

return --help option

- service not using "--defaults-file" can have any name not just "MySQL"
- service with "--defaults-file", without datadir in them
use default datadir (install_root\data)

MemorySanitizer (clang -fsanitize=memory) requires that all code
be compiled with instrumentation enabled. The only exception is the
C runtime library. Failure to use instrumented libraries will cause
bogus messages about memory being uninitialized.

In WITH_MSAN builds, we must avoid calling getservbyname(),
because even though it is a standard library function, it is
not instrumented, not even in clang 10.

Note: Before MariaDB Server 10.5, ./mtr will typically fail
due to the old PCRE library, which was updated in MDEV-14024.

The following cmake options were tested on 10.5
in commit 94d0bb4d:

cmake \
-DCMAKE_C_FLAGS='-march=native -O2' \
-DCMAKE_CXX_FLAGS='-stdlib=libc++ -march=native -O2' \
-DWITH_EMBEDDED_SERVER=OFF -DWITH_UNIT_TESTS=OFF -DCMAKE_BUILD_TYPE=Debug \
-DWITH_INNODB_{BZIP2,LZ4,LZMA,LZO,SNAPPY}=OFF \
-DPLUGIN_{ARCHIVE,TOKUDB,MROONGA,OQGRAPH,ROCKSDB,CONNECT,SPIDER}=NO \
-DWITH_SAFEMALLOC=OFF \
-DWITH_{ZLIB,SSL,PCRE}=bundled \
-DHAVE_LIBAIO_H=0 \
-DWITH_MSAN=ON

MEM_MAKE_DEFINED(): An alias for VALGRIND_MAKE_MEM_DEFINED()
and __msan_unpoison().

MEM_GET_VBITS(), MEM_SET_VBITS(): Aliases for
VALGRIND_GET_VBITS(), VALGRIND_SET_VBITS(), __msan_copy_shadow().

InnoDB: Replace the UNIV_MEM_ macros with corresponding MEM_ macros.

ut_crc32_8_hw(), ut_crc32_64_low_hw(): Use the compiler built-in
functions instead of inline assembler when building WITH_MSAN.
This will require at least -msse4.2 when building for IA-32 or AMD64.
The inline assembler would not be instrumented, and would thus cause
bogus failures.

mariabackup tries to allocate a buffer of page_size*page_size/4 size.
for 64k page it means 1Gb, which doesn't work very well on 32-bit builders.

Skip the 64k page test on 32bit.

and remove it on error

Disable existing non-empty datadir for mysql_install_db.exe

* fix FindLZ4 to follow convention (LIBRARIES, not LIBRARY)
* remove redundant checks from rocksdb/CMakeLists.txt
* put all checks through the same macro that uniformly
  checks for a package, prints the message, adds definition

The library finder needs to have capitals in its name so that FIND_PACKAGE
will load the correct finder and actually detect that libzstd is available.

Without this change the CMake would just always silently skip ZSTD since
it would never find it.

Simplify Debian autopkgtest RocksDB part and make it more verbose so that
future regressions like this are easier to debug.

Also remove QUIET from the RocksDB FIND_PACKAGE call so that it is easier
to read in build logs what libraries were detected. Also add missing
underscores to error messages.