Fixes after review and correction of the problems caused by the fact that during the SST innodb plugin is not yet initialized, as well as problems with running tests from the root user (not directly related to the MDEV-10754).

InnoDB executed code that is mean to execute only when Galera
is used and in bad luck one of the transactions is selected
incorrectly as deadlock victim. Fixed by adding wsrep_on_trx()
condition before entering actual Galera transaction handling.

No always repeatable test case for this issue is known.

After the commit b76b69cd
loose index scan for queries with DISTINCT stopped working.
That is why that commit has to be reverted.
Additionally this patch  fixes the problem of MDEV-10880.

MDEV-15511 - Use stunnel during rsync SST if available

Use table_arg that was passed to the function, instead of dereferencing
this->table, which is a NULL pointer.

fts_query(): Remove a redundant condition (result will never be NULL),
and instead check if *result is NULL, to prevent SIGSEGV in
fts_query_free_result().

The functions fts_ast_visit() and fts_query() inside
InnoDB FULLTEXT INDEX query processing are not checking
for THD::killed (trx_is_interrupted()), like anything
that potentially takes a long time should do.

This is a port of the following change from MySQL 5.7.23,
with a completely rewritten test case.

commit c58c6f8f66ddd0357ecd0c99646aa6bf1dae49c8
Author: Aakanksha Verma <aakanksha.verma@oracle.com>
Date:   Fri May 4 15:53:13 2018 +0530

Bug #27155294 MAX_EXECUTION_TIME NOT INTERUPTED WITH FULLTEXT SEARCH USING MECAB

This is a backport of the following fix from MySQL 5.7.23.
Some code refactoring has been omitted, and the test case has
been adapted to MariaDB.

commit 7a689acaa65e9d602575f7aa53fe36a64a07460f
Author: Krzysztof Kapuścik <krzysztof.kapuscik@oracle.com>
Date:   Tue Mar 13 12:34:03 2018 +0100

Bug#27082268 Invalid FTS sync synchronization

The fix closes two issues:
Bug #27082268 - INNODB: FAILING ASSERTION: SYM_NODE->TABLE != NULL DURING FTS SYNC
Bug #27095935 - DEADLOCK BETWEEN FTS_DROP_INDEX AND FTS_OPTIMIZE_SYNC_TABLE

Both issues were related to a FTS cache sync being done during
operations that perfomed DDL actions on internal FTS tables
(ALTER TABLE, TRUNCATE). In some cases the FTS tables and/or
internal cache structures could get removed while still being
used to perform FTS synchronization leading to crashes. In other
the sync operations could not get finishes as it was waiting for
dict lock which was taken by thread waiting for the background
sync to be finished.

The changes done includes:
- Stopping background operations during ALTER TABLE and TRUNCATE.
- Removal of unused code in FTS.
- Cleanup of FTS sync related code to make it more readable and
easier to maintain.

RB#18262

We did not merge Percona XtraDB 5.6.40-84.0 yet.
The changes in it are mostly cosmetic, except for
2 bug fixes from Oracle MySQL 5.6.40, which could
be security bugs.

This was achieved by taking the applicable parts
of an earlier InnoDB commit to XtraDB:

git diff 15ec8c2f{~,} storage/innobase|
sed -e s+/innobase/+/xtradb/+|patch -p1

No commit message

Problem:
As part of bug #24938374 fix, dict_operation_lock was not taken by
fts_optimize_thread while syncing fts cache.
Due to this change, alter query is able to update SYS_TABLE rows
simultaneously. Now when fts_optimizer_thread goes open index table,
It doesn't open index table if the record corresponding to that table is
set to REC_INFO_DELETED_FLAG in SYS_TABLES and hits an assert.

Fix:
If fts sync is already in progress, Alter query would wait for sync to
complete before renaming table.

RB: #19604
Reviewed by : Jimmy.Yang@oracle.com

This is motivated by Oracle MySQL Bug #27542720 SCHEMA MISMATCH
- TABLE FLAGS DON'T MATCH, BUT FLAGS ARE NUMBERS
but using a different approach.

row_import::match_schema(): In case of a mismatch, display the
ROW_FORMAT and optionally KEY_BLOCK_SIZE of the .cfg file.

We do not accept:
1. We did not have this problem (fixed earlier and better)
 d982e717 Bug#27510150: MYSQLDUMP FAILS FOR SPECIFIC --WHERE CLAUSES
2. We do not have such options (an DBUG_ASSERT put just in case)
 bbc2e37f Bug#27759871: BACKRONYM ISSUE IS STILL IN MYSQL 5.7
3. Serg fixed it in other way in this release:
 e48d775c Bug#27980823: HEAP OVERFLOW VULNERABILITIES IN MYSQL CLIENT LIBRARY

Test case was not written correctly.

If innodb_data_home_dir path specified in the configuration file
then rsync IST/SST will fail because the wsrep_sst_rsync.sh script
does not read this parameter from the configuration file and then
tries to find the data files in the default directory.

To fix this error, we need to add reading of the innodb_data_home_dir
configuration parameter to the rsync-related SST script.