lock_trx_release_locks(): Relax a debug assertion to allow
recovered TRX_STATE_COMMITTED_IN_MEMORY transactions.

trx_commit_in_memory(): Add DEBUG_SYNC instrumentation.

trx_undo_insert_cleanup(): Skip persistent changes if innodb_read_only
is set. This should only happen when a recovered committed transaction
would be cleaned up at shutdown.

The update was lost during merge.

Before killing the server, we have to FLUSH TABLES in order to
prevent the corruption of any MyISAM system tables.

PageConverter::adjust_cluster_record(): Instead of writing
the invalid value DB_ROLL_PTR=0, write a value that indicates
a fresh insert, that is, prevents the DB_ROLL_PTR from being
dereferenced in any circumstances.

It can be argued that IMPORT TABLESPACE should actually
update the dict_index_t::trx_id to prevent older transactions
from accessing the table, similar to what I did on table
rebuild in MySQL 5.6.6 in
https://github.com/mysql/mysql-server/commit/03f81a55f221095d397c375afe8a10c8038da339

Use unsigned comparison.

Suppress some messages that are emitted rarely
(when the FIL_PAGE_FILE_FLUSH_LSN of the first page of ibdata1
does not match the latest redo log checkpoint).

Do not unwrap view references to keep table info.
(Row-IN subselect does not unwrap items so it does not need fix)

only do it in EXTRA_DEBUG builds

Whenever one copies an IO_CACHE struct, one must remember to call
setup_io_cache, if not, the IO_CACHE's current_pos and end_pos
self-references will point to the previous struct's memory, which
could go out of scope. Commit 90038693
fixes this problem in a more general fashion by removing the
self-references altogether, but for 5.5 we'll keep the old behaviour.

MDEV-15014 Assertion `m_cache_lock_status == LOCKED_NO_WAIT || m_cache_status == DISABLE_REQUEST' failed in Query_cache::free_cache on startup

The assert guards against not-locked or not-requested query cache
disabling. If during startup we disable query cache, we failed to
request disabling.

        The thd->lex->part_info should be kept intact during PS
        execution. Or the second execution gets that modified part_info.
        Let's modify ths->work_part_info instead.

Item_xml_str_func::fix_fields() used a local "String tmp" as a buffer
for args[1]->val_str(). "tmp" was freed at the end of fix_fields(),
while Items created during my_xpath_parse() still pointed to its fragments.

Adding a new member Item_xml_str_func::m_xpath_query and store the result
of args[1]->val_str() into it.

To disable debug instrumentation, save and restore the original value
of the variable DEBUG_DBUG. Assigning -d,... will enable the output of
a lot of unrelated DBUG messages to the server error log.

To disable debug instrumentation, save and restore the original value
of the variable DEBUG_DBUG. Assigning -d,... will enable the output of
a lot of unrelated DBUG messages to the server error log.

This reverts commit 3486135b.

The commit comment ended in the words: "This is needed later."
Apparently the "later" never arrived.

The patch was brought in from 5.6.39 merge and we don't need it in
MariaDB

MDEV-11539 test_if_reopen: Assertion `strcmp(share->unique_file_name,filename) || share->last_version' failed upon select from I_S

remove HA_EXTRA_PREPARE_FOR_RENAME - neither OPTIMIZE nor REPAIR need it
(was introduced in b58e7956 when replacing remove_table_from_cache()
with wait_while_table_is_used() even though remove_table_from_cache()
did not have it).

The test checks the new sys_var added to xtradb from Percona

We don't need to print an error when loading kernel32.dll. If we can't
load it we'll automatically crash. Reviewed by wlad@mariadb.com

The patches are implemented using server changes in THD. We are not
interested in having special code for certain storage engines, if
possible.

This was a leftover post 5.5->10.0 merge. It should've been deleted
there.

Main additions:

commit 543c2006a70983c2ce75024bce3679b0c20f9ae6
Author: Olivier Bertrand <bertrandop@gmail.com>
Date:   Thu Jan 4 13:51:13 2018 +0100

    - Fix MDEV-9844, MDEV-10179, MDEV-14214
     This is done by removing the tbl table type THREAD option
     that causes a multiple of sporadic bugs.
     This may be temporary depending on whether a real fix is found.
      modified:   storage/connect/mysql-test/connect/disabled.def
      modified:   storage/connect/tabtbl.cpp
      modified:   storage/connect/tabtbl.h

commit 54bc4ea024ca5fb5c137c618084d8cccfba2ee3f
Author: Olivier Bertrand <bertrandop@gmail.com>
Date:   Fri Nov 3 16:21:56 2017 +0100

    - Fix MDEV-13925: Actually this fixes SELECT queries when
      the WHERE clause have single quote.
      modified:   storage/connect/ha_connect.cc

    - Use Windows VirtualAlloc and VirtualFree for the Sarea workspace
      modified:   storage/connect/global.h
      modified:   storage/connect/ha_connect.cc
      modified:   storage/connect/jsonudf.cpp
      modified:   storage/connect/plgdbutl.cpp
      modified:   storage/connect/plugutil.cpp
      modified:   storage/connect/user_connect.cc

    - Change inihandl from c to c++.
      Because it now includes global.h that contains a bool function definition
      that make compile to fail on Linux.
      modified:   storage/connect/CMakeLists.txt
      removed:    storage/connect/inihandl.c
      added:      storage/connect/inihandl.cpp

    - Fix MDEV-13860 CONNECT engine does not build with JDBC without ODBC.
      By including Sergei's patch in connect_assisted_discovery.
      modified:   storage/connect/ha_connect.cc

commit c07064d31a4d7ee0533fec144648d93873c0dd17
Author: Olivier Bertrand <bertrandop@gmail.com>
Date:   Wed Oct 18 00:11:00 2017 +0200

    - Update version number
      modified:   storage/connect/ha_connect.cc

    - Include MONGO in all Java enabled distributions
      Mongo will be enabled only for 10.2 and 10.3
      modified:   storage/connect/CMakeLists.txt

    - Change JDBC_SUPPORT to JAVA_SUPPORT which also replaces MONGO_SUPPORT
      MONGO_SUPPORT is now just used to enable the MONGO table type
      modified:   storage/connect/filter.cpp
      modified:   storage/connect/ha_connect.cc
      modified:   storage/connect/ha_connect.h
      modified:   storage/connect/mongo.cpp
      modified:   storage/connect/mycat.cc
      modified:   storage/connect/plgdbutl.cpp
      modified:   storage/connect/tabjson.cpp
      modified:   storage/connect/tabjson.h

    - Move MakeSelector function from FILTER to mongo.cpp
      modified:   storage/connect/filter.cpp
      modified:   storage/connect/filter.h
      modified:   storage/connect/cmgoconn.cpp
      modified:   storage/connect/jmgoconn.cpp
      modified:   storage/connect/mongo.cpp

    - Do mongo_init only on first use of the MongoDB C Driver
      This will permit to delay load the mongo lib on Windows
      modified:   storage/connect/cmgoconn.cpp
      modified:   storage/connect/cmgoconn.h
      modified:   storage/connect/ha_connect.cc

    - Replace NEW_VAR by a test on MYSQL_VERSION_ID
      modified:   storage/connect/ha_connect.cc

    - Suppress enable_mongo session variable
      modified:   storage/connect/ha_connect.cc
      modified:   storage/connect/mycat.cc

    - Make some function headers identical in .h and .cc file
      (replacing const char* by PCSZ)
      modified:   storage/connect/ha_connect.cc
      modified:   storage/connect/ha_connect.h

    - Change a parameter type from uchar* to const uchar*
      (for ScanRecord and CheckRecord)
      modified:   storage/connect/ha_connect.cc
      modified:   storage/connect/ha_connect.h

    - Changes on LIKE and NOT LIKE does not fix a bug yet
      modified:   storage/connect/ha_connect.cc

    - Suppress PIVOT_SUPPORT (PIVOT type is unconditionnal)
      modified:   storage/connect/ha_connect.cc
      modified:   storage/connect/mycat.cc

    - Change the strz function from inline to static
      modified:   storage/connect/ha_connect.cc
      modified:   storage/connect/ha_connect.h

    - export the JavaConn class and the MgoColumns and IsNum functions
      modified:   storage/connect/javaconn.h
      modified:   storage/connect/json.h
      modified:   storage/connect/mongo.h

    - Fix MDEV-13924
      modified:   storage/connect/jdbconn.cpp

    - Make a temporary fix for the compiler bug in CalculateArray
      modified:   storage/connect/jsonudf.cpp
      modified:   storage/connect/tabjson.cpp

    - Typo
      modified:   storage/connect/jdbccat.h
      modified:   storage/connect/reldef.h
      modified:   storage/connect/tabext.h
      modified:   storage/connect/tabjmg.cpp
      modified:   storage/connect/tabxml.h
      modified:   storage/connect/valblk.h
      modified:   storage/connect/value.h
      modified:   storage/connect/xtable.h

    - Fix a bug in MONGO tests by changing 'MONGO' to $TYPE
      modified:   storage/connect/mysql-test/connect/t/mongo_test.inc

    - Record test results to reflect all changes
      modified:   storage/connect/mysql-test/connect/r/json_java_2.result
      modified:   storage/connect/mysql-test/connect/r/json_java_3.result
      modified:   storage/connect/mysql-test/connect/r/json_mongo_c.result
      modified:   storage/connect/mysql-test/connect/r/mongo_c.result
      modified:   storage/connect/mysql-test/connect/r/mongo_java_2.result
      modified:   storage/connect/mysql-test/connect/r/mongo_java_3.result

commit 3da90fd112e7d5ee6f0bd9c3fc3eeb4529b30e93
Author: Olivier Bertrand <bertrandop@gmail.com>
Date:   Wed Oct 11 12:21:56 2017 +0200

    Fix MDEV-13924 modified: storage/connect/jdbconn.cpp

commit 2566e67da80f291414f02c7dd6a8ca3557161d26
Author: Olivier Bertrand <bertrandop@gmail.com>
Date:   Mon Sep 11 16:38:41 2017 +0200

    Enable MONGO for the C driver. Modified: modified:   storage/connect/CMakeLists.txt

commit 27ae11db830c5d62bbf8b8b13cab976b74efe7dd
Author: Olivier Bertrand <bertrandop@gmail.com>
Date:   Tue Sep 5 19:52:04 2017 +0200

    - Update version number
      modified:   storage/connect/ha_connect.cc

    - Regard columns with binary charset as string (was binary)
      modified:   storage/connect/ha_connect.cc
      modified:   storage/connect/tabmysql.cpp
      modified:   storage/connect/tabutil.cpp

    - Support length 0 for CHAR and VARCHAR
      modified:   storage/connect/ha_connect.cc
      modified:   storage/connect/reldef.cpp
      modified:   storage/connect/value.cpp

    - Add ACCEPT option for void columns in discovery
      modified:   storage/connect/tabjson.cpp

    - Update some tests because of above change
      modified:   storage/connect/mysql-test/connect/r/json_java_2.result
      modified:   storage/connect/mysql-test/connect/r/json_java_3.result
      modified:   storage/connect/mysql-test/connect/r/json_mongo_c.result
      modified:   storage/connect/mysql-test/connect/r/mongo_c.result
      modified:   storage/connect/mysql-test/connect/r/mongo_java_2.result
      modified:   storage/connect/mysql-test/connect/r/mongo_java_3.result
      modified:   storage/connect/mysql-test/connect/r/odbc_oracle.result
      modified:   storage/connect/mysql-test/connect/r/updelx.result
      modified:   storage/connect/mysql-test/connect/t/mongo_test.inc

commit f6ee6cd1d42d861fa50fea8d9a7079347b7ddfd6
Author: Olivier Bertrand <bertrandop@gmail.com>
Date:   Sat Sep 2 16:06:10 2017 +0200

    - Fix MongoDB C Driver adding for CMAKE.
      Requires MongoDB C Driver version 1.7 now available
      modified:   storage/connect/CMakeLists.txt

    - Add more trace to tbl_thread.test (to debug failure)
      modified:   storage/connect/mysql-test/connect/r/tbl_thread.result
      modified:   storage/connect/mysql-test/connect/t/tbl_thread.test

First roll back changes, then free Items which can lead to memory freeing.

Backport 7c03edf2 from xtradb to innodb

also cover USE and other built-in commands