Bug #25167032 CRASH WHEN ASSIGNING MY_ERRNO - MISSING MY_THREAD_INIT IN BACKGROUND THREAD

Description:
===========
Add my_thread_init() and my_thread_exit() for background threads which
initializes and frees the st_my_thread_var structure.

Reviewed-by: Jimmy Yang<jimmy.yang@oracle.com>
RB: 15003

storage/innobase/buf/buf0dump.cc

 /*****************************************************************************
 
-Copyright (c) 2011, 2016, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2017, MariaDB Corporation. All Rights Reserved.
+Copyright (c) 2011, 2017, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 2017, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -796,6 +796,7 @@ extern "C"
 os_thread_ret_t
 DECLARE_THREAD(buf_dump_thread)(void*)
 {
+	my_thread_init();
 	ut_ad(!srv_read_only_mode);
 	/* JAN: TODO: MySQL 5.7 PSI
 #ifdef UNIV_PFS_THREAD
@@ -836,6 +837,7 @@ DECLARE_THREAD(buf_dump_thread)(void*)
 
 	srv_buf_dump_thread_active = false;
 
+	my_thread_end();
 	/* We count the number of threads in os_thread_exit(). A created
 	thread should always use that to exit and not use return() to exit. */
 	os_thread_exit();

storage/innobase/log/log0recv.cc

 /*****************************************************************************
 
-Copyright (c) 1997, 2016, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 1997, 2017, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2012, Facebook Inc.
 Copyright (c) 2013, 2017, MariaDB Corporation.
 
@@ -532,6 +532,7 @@ DECLARE_THREAD(recv_writer_thread)(
 			/*!< in: a dummy parameter required by
 			os_thread_create */
 {
+	my_thread_init();
 	ut_ad(!srv_read_only_mode);
 
 #ifdef UNIV_PFS_THREAD
@@ -568,6 +569,7 @@ DECLARE_THREAD(recv_writer_thread)(
 
 	recv_writer_thread_active = false;
 
+	my_thread_end();
 	/* We count the number of threads in os_thread_exit().
 	A created thread should always use that to exit and not
 	use return() to exit. */

storage/innobase/trx/trx0roll.cc

 /*****************************************************************************
 
-Copyright (c) 1996, 2016, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 1996, 2017, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2016, 2017, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
@@ -868,6 +868,8 @@ DECLARE_THREAD(trx_rollback_or_clean_all_recovered)(
 			/*!< in: a dummy parameter required by
 			os_thread_create */
 {
+	my_thread_init();
+
 	ut_ad(!srv_read_only_mode);
 
 #ifdef UNIV_PFS_THREAD
@@ -878,6 +880,7 @@ DECLARE_THREAD(trx_rollback_or_clean_all_recovered)(
 
 	trx_rollback_or_clean_is_active = false;
 
+	my_thread_end();
 	/* We count the number of threads in os_thread_exit(). A created
 	thread should always use that to exit and not use return() to exit. */