If mysql_lock_tables fails because the lock was aborted, we need to
reset thd->some_tables_delete, otherwise we might loop indefinitely
because handler's tables are not closed in a standard way, meaning
that close_thread_tables() (which resets some_tables_deleted) is not
used.

This patch fixes sporadical failures of handler_myisam/innodb tests
which were introduced by previous fix for this bug.