ha_innobase_inplace_ctx::create_key_defs(): Replaces
innobase_create_key_defs().

dict_index_t::contains_col_or_prefix(): Replaces
dict_index_contains_col_or_prefix().

Closes #988

Bug was introduced in this commit:

  commit: a9ca8198
      Call alloc() instead of realloc()
      Use alloc() if we don't need original string (avoid copy)
      Removed not needed test of str_length in sql_string.cc

copy_if_not_alloced() was forgotten when changing realloc()'s to alloc()'s.
Changing it now.

MDEV-18224 MTR's internal check of the test case 'innodb.recovery_shutdown' failed due to extra #sql-ib*.ibd files

The test innodb.recovery_shutdown would occasionally fail,
because recovered incomplete transactions would be conflicting
with DROP TABLE, causing the background drop table queue to be invoked.

Add a slow shutdown before dropping the tables, so that the
recovered transactions will be rolled back. Starting with MDEV-14705,
normal shutdown would abort the rollback of recovered transactions.

The purpose of buf_pool->flush_rbt is to ensure that
buf_pool->flush_list is ordered by oldest_modification.
This should speed up multi-pass redo log application
(when the buffer pool is not large enough to accommodate
all pages that were modified since the latest log checkpoint).

The buf_pool->flush_rbt is not being used after redo log has
been applied. It could be better to always flush pages in
the ascending order of oldest_modification. Currently, whenever
a page is first modified, it will be moved to the start of the
buf_pool->flush_list, overtaking blocks whose oldest_modification
could be much older.

buf_flush_insert_sorted_into_flush_list(): Merge into
buf_flush_insert_into_flush_list().

buf_flush_recv_note_modification(): Remove.
The function buf_flush_note_modification() can be invoked instead.

btr_cur_pessimistic_insert(): Do not attempt to convert the
metadata BLOB to external storage if it has already been converted.
It could have been converted by btr_cur_pessimistic_update().
Relax some over-zealous assertions.

dtuple_convert_big_rec(): Assert that the metadata BLOB has
not been converted yet.

btr_cur_instant_init_low(): Fix the typo in the computation
of the trx_id_offset of a metadata record.

Simplified mutex code. MutexDebug uses OSMutex instead of
atomic operations now.

MDEV-15022 - travis: add versioning to test suite

MDEV-15578 - travis: add zstd for osx

- Changed the performance schema query which gives sampling with event
counting. It should fix the issue.

dict_table_t::instant_column(): Correctly compute the value of
metadata_changed. The original computation in
commit 00372075 would essentially
invoke memcmp(x,x,y), which can only return 0.

buf_page_t::buf_fix_count transition to Atomic_counter.

Replaced srv_fatal_semaphore_wait_threshold juggling with
btr_validate_index_running counter.
Removed last argument of btr_validate_index(): always false.
Simplified away btr_validate_spatial_index().

Make mariabackup.sh compatible on FreeBSD

Fix an inadvertently inverted condition that caused
galera.galera_sst_mariabackup_table_options test failure.