- Add new submodule for WolfSSL
- Build and use wolfssl and wolfcrypt instead of yassl/taocrypt
- Use HAVE_WOLFSSL instead of HAVE_YASSL
- Increase MY_AES_CTX_SIZE, to avoid compile time asserts in my_crypt.cc
(sizeof(EVP_CIPHER_CTX) is larger on WolfSSL)

trx_rseg_array_init(): Using the 10.4 specific MLOG_MEMSET record,
clear the entire TRX_SYS_WSREP_XID_INFO field.

Check locking options and brackets combinations.

Bootstrapping a new cluster from a backup created from a MariaDB
version prior to 10.3.5 may result in error "SST position can't be
set in past" when attempting to join additional nodes.
The problem stems from the fact that when reading the wsrep position
from InnoDB, the position is looked up in two places:
the TRX_SYS page, where versions prior to 10.3.5 used to store
WSREP's position; and rollback segments, this is where newer versions
store the position.
When starting a new cluster, the starting seqno is 0 and a new cluster
UUID is generated. This is persisted in rollback segments, but the old
UUID and seqno are not cleared from TRX_SYS page.
Subsequently, when reading back the position,
trx_rseg_read_wsrep_checkpoint() is going to return the maximum seqno
found in both TRX_SYS page and rollback segments. So in the case of a
newly bootstrapped cluster, it's always going to return the old
cluster information.
The fix consists of changing trx_rseg_read_wsrep_checkpoint() so that
only rollback segments are looked up. On startup, position is read
from the TRX_SYS page, and if present, it is copied to rollback
segments (unless a newer position is already present in the rollback
segments).
Finally the position stored in TRX_SYS page is cleared.

MDEV-19524 Server crashes in Bitmap<64u>::is_clear_all / Field_longstr::csinfo_change_allows_instant_alter

compare_keys_but_name(): reorder checks to ensure that
new_field->field != NULL inside Field::is_equal()

[Closes tempesta-tech/mariadb#572]

Disallow DATETIME for SYSTEM VERSIONING tables.

MDEV-19486 Server crashes in row_upd or row_upd_del_mark_clust_rec on REPLACE into a versioned table

row_insert_for_mysql(): InnoDB sets values for row_start and row_end.
And this function used to return those values to server in
ha_innobase::write_row().  This buggy behavior was removed. Also,
a piece of code in this function was reformatted.

upd_node_t::make_versioned_helper(): Assert that the preallocated size
of the update vector is not exceeded.

The issue in this case is that we take in account the estimates from quick keys instead of rec_per_key.
The estimates for quick keys are better than rec_per_key only if we have ref(const), so we need to check
that all keyparts in the ref key are of the type ref(const).

* add error for truncation of versioned tables: `ER_TRUNCATE_ILLEGAL_VERS`
* make a full table open with `tdc_aquire_share` instead of just `ha_table_exists` check
test suites run: main, parts, versioning

Closes #785

Closes #1212

Fixing a test failure tokudb.change_column_varbin_descriptor

Always initialize dict_sys.m_initialised.

dict_sys.lock(), dict_sys_lock(): Acquire both mutex and latch.

dict_sys.unlock(), dict_sys_unlock(): Release both mutex and latch.

dict_sys.assert_locked(): Assert that both mutex and latch are held.

The magic_n only complicated object destruction and did not serve
any useful purpose.

* Versioning tests support

Closes #1043

handler::write_row() should not destroy the state of the running
index_search/index_next/... or rnd_init/rnd_next/... scan

Closes #677

Improve diagnostics. Try to guess what type user tried to type.

dict_sys_t::create(): Renamed from dict_init().

dict_sys_t::close(): Renamed from dict_close().

dict_sys_t::add(): Sliced from dict_table_t::add_to_cache().

dict_sys_t::remove(): Renamed from dict_table_remove_from_cache().

dict_sys_t::prevent_eviction(): Renamed from
dict_table_move_from_lru_to_non_lru().

dict_sys_t::acquire(): Replaces dict_move_to_mru() and some more logic.

dict_sys_t::resize(): Renamed from dict_resize().

dict_sys_t::find(): Replaces dict_lru_find_table() and
dict_non_lru_find_table().

JSON_MERGE_PATCH implemented. Added JSON_MERGE_PRESERVE as a synonim for
the JSON_MERGE.