Merge into the MariaDB tree the pull request from Rich Prohaska for
PerconaFT. These changes are needed to get parallel replication to
work with TokuDB. Once the pull request is accepted by Percona and the new upstream version enters MariaDB, this commit can be superseded.

Original commit message from Rich Prohaska:

    1. Fix the release before wait race

    The release before wait race occurs when a lock is released by transaction A after transaction B tried to acquire it but before transaction B has a chance to register it's pending lock request.  There are several ways to fix this problem, but we want to optimize for the common situation of minimal lock conflicts, which is what the lock acquisition algorithm currently does.  Our solution to the release before wait race is for transaction B to retry its lock request after its lock request has been added to the pending lock set.

    2. Fix the retry race

    The retry race occurs in the current lock retry algorithm which assumes that if some transaction is running lock retry, then my transaction does not also need to run it.  There is a chance that some pending lock requests will be skipped, but these lock requests will eventually time out.  For applications with small numbers of concurrent transactions, timeouts will frequently occur, and the application throughput will be very small.

    The solution to the retry race is to use a group retry algorithm.  All threads run through the retry logic.  Sequence numbers are used to group retries into batches such that one transaction can run the retry logic on behalf of several transactions.  This amortizes the retry cost.  The sequence numbers also ensure that when a transaction releases its locks, all of the pending lock requests that it is blocking are retried.

    3. Implement a mechanism to find and kill a pending lock request

    Tags lock requests with a client id, use the client id as a key into the pending lock requests sets to find a lock request, complete the lock request with a lock timeout error.

    Copyright (c) 2016, Rich Prohaska
    All rights reserved.

    Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

    2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Fixed the 'wsrep_replicate_myisam' check to allow only limited
set of commands. Added a debug assert to discover such cases.

Update test case.

Internal updates to system statistical tables could wrongly
trigger an additional total-order replication if wsrep_repli
-cate_myisam is enabled.
Fixed by adding a check to skip total-order replication for
stat tables.

Test: galera.galera_var_replicate_myisam_on

thd->variables.option_bits need to be restored after
plugin_thdvar_init() during post initialization of
wsrep threads.

fix the tokudb_analyze_in_background_basic test to run on mariadb.  mariadb does additional value checking for boolean system variables

MDEV-10408 run the tokudb_rpl.rpl_rfr_disable_on_expl_pk_absence test.  Add control files.  Fixup result file for mariadb

MDEV-11182: InnoDB: Assertion failure in file buf0buf.cc line 4730 (encryption.create_or_replace fails in buildbot and outside)

Analysis: Problem is that page is encrypted but encryption information
on page 0 has already being changed.

Fix: If page header contains key_version != 0 and even if based on
current encryption information tablespace is not encrypted we
need to check is page corrupted. If it is not, then we know that
page is not encrypted. If page is corrupted, we need to try to
decrypt it and then compare the stored and calculated checksums
to see is page corrupted or not.

intentionally produces this error.

Add error message when used index_id in index page is not found
from configuration file.

Removed experimental from message.

Two problems:

(1) When pushing warning to sql-layer we need to check that thd != NULL
to avoid NULL-pointer reference.

(2) At tablespace key rotation if used key_id is not found from
encryption plugin tablespace should not be rotated.

MDEV-10394: Innodb system table space corrupted

Analysis: After we have read the page in buf_page_io_complete try to
find if the page is encrypted or corrupted. Encryption was determined
by reading FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION field from FIL-header
as a key_version. However, this field is not always zero even when
encryption is not used. Thus, incorrect key_version could lead situation where
decryption is tried to page that is not encrypted.

Fix: We still read key_version information from FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION
field but also check if tablespace has encryption information before trying
encrypt the page.

AWS C++ SDK always defaults region to us-east-1 for clientConfiguration
(ignoring config file or env.variable)

This patch introduces a plugin variable 'region' to make it usable
for master keys created in regions other than 'us-east-1'.

Update test results after 26b87c33

In the function create_key_parts_for_pseudo_indexes()
the key part structures of pseudo-indexes created for
BLOB fields were set incorrectly.
Also the key parts for long fields must be 'truncated'
up to the maximum length acceptable for key parts.

1. When min/max value is provided the null flag for it must be set to 0
in the bitmap Culumn_statistics::column_stat_nulls.
2. When the calculation of the selectivity of the range condition
over a column requires min and max values for the column then we
have to check that these values are provided.

           'mysql.proc' doesn't exist.

        The mysql_rm_db() doesn't seem to expect the 'mysql' database
        to be deleted. Checks for that added.
        Also fixed the bug MDEV-11105 Table named 'db'
        has weird side effect.
        The db.opt file now removed separately.

cherry-pick from 5.7:
  commit 6b24763
  Author: Manish Kumar <manish.4.kumar@oracle.com>
  Date:   Tue Mar 27 13:10:42 2012 +0530

  BUG#12977988 - ON STOP SLAVE: ERROR READING PACKET FROM SERVER: LOST CONNECTION
                 TO MYSQL SERVER
  BUG#11761457 - ERROR 2013 + "ERROR READING RELAY LOG EVENT" ON STOP SLAVEBUG#12977988 - ON STOP SLAVE: ERROR READING PACKET FROM SERVER: LOST CONNECTION
               TO MYSQL SERVER

Problem was that if old virtual column is computed and stored there
was no check if new column is really virtual column.