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.

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.

fix test result of sys_vars.slave_transaction_retry_errors

Add the following parameter.

- spider_sync_sql_mode
  Local sql_mode synchronous existence to remote server.
   0 : It doesn't synchronize.
   1 : It synchronizes.
  The default value is 1

On clang, use __builtin_readcyclecounter() when available.
Hinted by Sergey Vojtovich. (This may lead to runtime failure
on ARM systems. The hardware should be available on ARMv8 (AArch64),
but access to it may require special privileges.)

We remove support for the proprietary Sun Microsystems compiler,
and rely on clang or the __GNUC__ assembler syntax instead.

For now, we retain support for IA-64 (Itanium) and 32-bit SPARC,
even though those platforms are likely no longer widely used.

We remove support for clock_gettime(CLOCK_SGI_CYCLE),
because Silicon Graphics ceased supporting IRIX in December 2013.
This was the only cycle timer interface available for MIPS.

On PowerPC, we rely on the GCC 4.8 __builtin_ppc_get_timebase()
(or clang __builtin_readcyclecounter()), which should be equivalent
to the old assembler code on both 64-bit and 32-bit targets.

error code 12701 is already included in default value, but other plugin specific error codes are ignored because of checking with ER_ERROR_LAST. ER_ERROR_LAST does not include plugin specific error codes. So I just removed it for fixing this issue.

The bug was that when long item-strings was converted to VARCHAR,
type_handler::string_type_handler() didn't take into account max
VARCHAR length.  The resulting Aria temporary table was created with
a VARCHAR field of length 1 when it should have been 65537. This caused
MariaDB to send impossible records to ma_write() and Aria reported
eventually the table as crashed.

Fixed by updating Type_handler::string_type_handler() to not create too long
VARCHAR fields. To make things extra safe, I also added checks in when
writing dynamic Aria records to ensure we find the wrong record during write
instead of during read.

We omit the work-around commit 0b7fa5a0
because it appears to be needed for CentOS 6 only,
which we no longer support.

On some platforms, MY_RELAX_CPU() falls back to an atomic
memory operation, but my_cpu.h fails to include my_atomic.h.

The RDTSC instruction, which was introduced in the Intel Pentium,
has been used in MariaDB for a long time. But, the __rdtsc()
wrapper is not available by default in some x86 build environments.
The simplest solution seems to replace the inlined instruction
with a call to the wrapper function my_timer_cycles(). The overhead
for the call should not affect the measurement threshold.

On Windows and on AMD64, we will keep using __rdtsc() directly.

Starting with the Intel Skylake microarchitecture, the PAUSE
instruction latency is about 140 clock cycles instead of earlier 10.
On AMD processors, the latency could be 10 or 50 clock cycles,
depending on microarchitecture.

Because of this big range of latency, let us scale the loops around
the PAUSE instruction based on timing results at server startup.

my_cpu_relax_multiplier: New variable: How many times to invoke PAUSE
in a loop. Only defined for IA-32 and AMD64.

my_cpu_init(): Determine with RDTSC the time to run 16 PAUSE instructions
in two unrolled loops according, and based on the quicker of the two
runs, initialize my_cpu_relax_multiplier. This form of calibration was
suggested by Mikhail Sinyavin from Intel.

LF_BACKOFF(), ut_delay(): Use my_cpu_relax_multiplier when available.

ut_delay(): Define inline in my_cpu.h.

UT_COMPILER_BARRIER(): Remove. This does not seem to have any effect,
because in our ut_delay() implementation, no computations are being
performed inside the loop. The purpose of UT_COMPILER_BARRIER() was to
prohibit the compiler from reordering computations. It was not
emitting any code.

MDEV-19585  Assertion with S3 table and flush_tables

The limit has to be increased so that MariaDB can create system tables.
It should not have any notable impact on performance.

There should not be any notable performance differences between 1K and 4K,
especially for temporary tables. In most cases using bigger blocks is also
faster (with the possible exception of doing key reads of not fixed length
keys).

The problem was two fault:
- flush_tables() wrongly gave errors when failing to open read only tables
- backup_block_ddl() didn't properly ignores errors from flush_tables()

The test case for this will be pushed in 10.5 as the test involves
S3 tables.

os0once.h: remove as not used now

zip_pad_info_t::mutex_created: remove along with corresponding stuff

zip_pad_info_t::mutex: make member value instead of a pointer

dict_table_t::stats_latch_created: remove along with related stuff

dict_table_t::stats_latch: make value member, not pointer. And always lock this
for simplicity, even to stats cloned table.

based on the work of Sergey Vojtovich

Get rid of os_once.

MDEV-19049 Server crashes in check_duplicate_long_entry_key, ASAN stack-buffer-overflow in Field_blob::get_key_image

Long Unique keys should always be last unique key.

Limit lines to ~16K

The bug occured when the optimizer decided to use a rowid filter built
by a range index scan to access an InnoDB table with generated clustered
index.
When a table is accessed by a secondary index Idx employing a rowid filter the
the value of pk contained in the found index tuple is checked against the
filter. A call of the handler function position is supposed to put the
pk value into the handler::ref buffer. However for generated clustered
primary keys it did not happened. The patch fixes this problem.