Recalculate distinct pointer if we cut chain of SELECTs

Initialize node->trx_id before checking if a table can be skipped.

wait_all_purged.inc: Wait for 60 seconds instead of 30 seconds.
Purge can be slow on buildbot, especially in ASAN-instrumented builds.

purge_node_t::in_progress: Replaces purge_node_t::done.
Only present in debug builds.

purge_node_t::start(): Moved from the start of row_purge_step().

purge_node_t::end(): Replaces row_purge_end().

trx_purge_attach_undo_recs(): Omit a check from non-debug builds.

If a table has been dropped, rebuilt, or its tablespace has been
discarded or the table is corrupted, it does not make sense to
look up that table again while purging old undo log records.

purge_node_t::purge_node_t(): Replaces row_purge_node_create().

que_common_t::que_common_t(): Constructor.

row_import_update_index_root(): Remove the constant parameter
dict_locked=true, and update the table->def_trx_id in the cache.

purge_node_t::unavailable_table_id: The latest unavailable table ID,
to avoid future lookups.

purge_node_t::def_trx_id: The latest modification of the table
identified by unavailable_table_id, or TRX_ID_MAX.

purge_node_t::is_skipped(): Determine if a table should be skipped.

purge_node_t::skip(): Note that a table should be skipped.

MTR tests for clearing orphaned SR transactions in Galera

Fixed sync points in MW-388 and fixed SP wsrep error handling to
avoid propagating wsrep errors via client-server protocol response.

This can be useful:
UBSAN_OPTIONS=log_path=/some/path

clang users may want to increase stack size in include/my_pthread.h or enable
some optimizations

Clean up after commit 0957d257
which introduced some disorder (unsorted or duplicated test names).

Removed redundant initialisation in unireg_init(): already done by
mysql_init_variables().

Slave threads already check THD::killed, which eliminates the need to
check abort_loop.

Removed unused wsrep_kill_mysql().

modified:   suite/galera/t/galera_autoinc_sst_mariabackup.test

remove WSREP_SST_OPT_SUFFIX_VALUE, checking [mysqld] is covered in the parse_cnf --mysqld case also in wsrep_sst_xtrabackup-v2

wsrep_sst: remove WSREP_SST_OPT_SUFFIX_VALUE, checking [mysqld] is covered in the parse_cnf --mysqld case

modified:   mysql-test/suite/galera/disabled.def
modified:   mysql-test/suite/galera/r/galera_many_rows.result
modified:   mysql-test/suite/galera/t/galera_kill_nochanges.test
new file:   mysql-test/suite/galera/t/galera_many_rows.cnf
modified:   mysql-test/suite/galera/t/galera_many_rows.test
modified:   mysql-test/suite/galera/t/galera_var_dirty_reads.test
modified:   scripts/wsrep_sst_mariabackup.sh

galera.partition and galera.galera_binlog_stmt_autoinc regularly display
mismatching values for AUTO_INCREMENT columns.

galera.MW-336 often times out while waiting for something in PROCESSLIST.

Also, sort the test names, remove the redundant "galera." prefix and
fix typos in 2 test names.

TVC uses derived as singlatable calls

- Fetch innodb_compression_level from the running server.Add the value
of innodb_compression_level in backup-my.cnf file during backup phase.
So that prepare can use the innodb_compression_level variable from
backup-my.cnf

When compiling CMAKE_BUILD_TYPE=Debug WITH_ASAN using clang-7 -O2
the following tests could fail due to insufficient stack size:
main.signal_demo3 sys_vars.max_sp_recursion_depth_func

In commit d30f17af the change of
the loop iteration broke another error handling path that did
"goto error_handling_drop_uncached". Cover this code path with
fault injection, and revert to the correct iteration.

There are two fault injection labels innodb_OOM_prepare_inplace_alter.
Their order was swapped in MDEV-11369, so that the label that used
to be covered in an ADD INDEX code path would become unreachable
because the label that is executed for any ALTER TABLE was executed
first. Let us introduce the label innodb_OOM_prepare_add_index
for the more specific case.

The 10.1 changes to the test case were accidentally omitted
in the merge commit 913e33e4.

The test case was accidentally omitted from the merge
commit 913e33e4.

GCC does not like MY_ATTRIBUTE((nonnull)) on a reference-to-pointer
parameter. clang did not flag an issue wit that.

Rewrite the MDEV-13818 fix to prevent heap-use-after-free.

Add a test case for MDEV-18272.

Part#2 (final): rewritting the code to pass the correct enum_sp_aggregate_type
to the sp_head constructor, so sp_head never changes its aggregation type
later on. The grammar has been simplified and defragmented.
This allowed to check aggregate specific instructions right after
a routine body has been scanned, by calling new LEX methods:
  sp_body_finalize_{procedure|function|trigger|event}()

Moving some C++ code from *.yy to a few new helper methods in LEX.