MDEV-19486 and one more similar bug appeared because handler::write_row() interface
welcomes to modify buffer by storage engine. But callers are not ready for that
thus bugs are possible in future.

handler::write_row():
handler::ha_write_row(): make argument const

Use on every virtual function override.

ha_innobase: mark a final

ha_innobase::bas_ext(): remove as unused

ha_innobase::get_cascade_foreign_key_table_list: remove as unused

ha_innobase::end_stmt(): merge into ha_innobase::reset()

Since 10.4 requires C++11 capable compiler, gcc sync builtins became
dead code. Remove relevant cmake checks and cleanup include files.

Even though the PAUSE instruction latency was increased from
about 10 to 140 clock cycles in the Intel Skylake microarchitecture,
it seems to be optimal to reduce the amount of subsequently executed
PAUSE instructions not to 1/14, but to 1/2.

Uniformly use the `.git` suffix format

* in --parallel mode don't copy/symlinks plugins individually
  in each forked child's vardir, use the common parent vardir with
  all plugins
* move pam plugin specific code from mysql-test-run.pl to
  suite/plugins/suite.pm

(meaning, if MariaDB is installed system-wide, pam tests
require mtr to be run as mysql user)

fixed in MDEV-19878, here just adding tests

* fix incorrect parentheses
* if there was no password on the command line or in .cnf file,
  pkt will be "", and we need to request the user to enter the password

* wait() for the child process to die, let it rest in peace
* fix incorrect parentheses
* if there was no password on the command line or in .cnf file,
  pkt will be "", and we need to request the user to enter the password
* make sure that auth->salt is always allocated on a permanent memroot.
  when called from set_user_salt_if_needed(), user_copy and its auth_str
  are on the thd memroot, but auth_copy->salt is then copied to auth->salt
* adjust service files so that systemd wouldn't interfere with our
  setuid executables

also
* print the pam error message in debug mode

in fact, permissions were fine in RPM, but mysql_install_db
was resetting them.

Also fix Debian, while we're at it

and install in mysql-test/suite/plugins/pam
so that it could be manually copied into /etc if needed

this matches the common behavior with pam_unix and helps to
catch password related errors

also, use abort() instead of sigsegv to avoid polluting
/var/log/messages with intentional crashes

in /etc/ssl/openssl.cnf

as it happens to be on the buster builder

MDEV-19716: ASAN use-after-poison in Query_log_event::Query_log_event / THD::log_events_and_free_tmp_shares

Analysis:
========
When a given client session ends on a master, the server logs a DROP TEMPORARY
TABLE IF EXISTS statement for each temporary table that still exists in the
current session. It ensures a proper temporary table cleanup on the slave. In
order to write the DROP TEMPORARY TABLE query in binary log a 'Query_log_event'
object is created. Within the 'Query_log_event' constructor
'thd->lex->sql_command' is read to identify what type of cache needs to be
used to write the query. When the code reaches here as part of THD::cleanup
the 'thd->lex->sql_command' will be in an invalid state. The 'thd->lex' could
have been cleared or it could be pointing to a statement which was in the
middle of execution when the session ended. In such cases ASAN reports
use-after-poison error.

Fix:
===
The 'THD::Cleanup' code invokes 'THD::log_events_and_free_tmp_shares' to look
for temporary tables and write appropriate DROP TABLE stmts for them. This
cleanup code provides a special flag named 'direct=TRUE' to the
Query_log_event constructor. Having 'direct=TRUE' means that this query
doesn't require any caching. Hence in this scenario the 'Query_log_event'
constructor should respect the 'direct' flag and simply skip the logic of
deciding the type of cache to be used for the statement. Hence the code will
not access the stale lex object.

- Changed the assert to ignore SRV_LOG_SPACE_FIRST_ID. Post push
fix to address the previous commit failure.

btr_lift_page_up(): Correct the incorrect condition.

page_validate(): Validate the page type.

page_validate(): Validate also the page type, and try to list all
errors that were encountered for the page, with a little more detail.

Changed the debug insert inside fil_io() to check whether it writes
the page to wrong offset only for user tablespace.

- log_crypt_init() should be called from create_log_files(). Because
it should re-create the new random nonce compared to the old ones.

The test innodb.leaf_page_corrupted_during_recovery
fails on buildbot with

Warning	1406	Data too long for column 'line' at row 10
line
 len 16384; hex ...

because of a page dumps that InnoDB is generating for a corrupted page

Since this test is using debug instrumentation, we will solve the
issue by disabling page dumps in debug builds altogether. Users of
debug builds will likely know how to extract page dumps in other means.

Page dump output could sometimes be useful when diagnosing problems
that users are facing. Hence we will keep the page dump output in
non-debug (release) builds.

MDEV-19914 Server startup fails while dropping garbage encrypted tablespace if innodb_encryption_threads > 0

- Avoiding accessing encryption thread mutex before initiating
the encryption threads

- Ported mysql Bug#20597981 test case to mariadb-10.2
- InnoDB never used fts_doc_id_in_read_set. Basically it tells
innodb to read the fts_doc_id from the index record itself.

fix test result of sys_vars.slave_transaction_retry_errors