>= M_TOT_PARTS' FAILED.

This patch is taken from MySQL, originally written by Mattias Jonsson
Here follows the original commit message:

Problem in handle_alter_part_error(),
result in altered partition_info object was still used
if table was under LOCK TABLES.

Solution was to always close and destroy all table
and table_share instances if exclusive mdl lock was
possible.
If not succeeding in get an exlusive lock (only possible
during rollback of DDL), at least close and destroy this
table instance.

rb#7361.
Approved by Mikael and Aditya.