of stored routines definitions even if we already have some tables open and
locked. To avoid deadlocks in this case we have to put certain restrictions
on locking of mysql.proc table.
This allows to use stored routines safely under LOCK TABLES without explicitly
mentioning mysql.proc in the list of locked tables. It also fixes bug #11554
"Server crashes on statement indirectly using non-cached function".
In order to make multi-delete SP friendly we need to have all table
locks for the elements of main statement table list properly set
at the end of parsing.
Also performed small cleanup: We don't need relink_tables_for_multidelete()
any longer since the only case now when TABLE_LIST::correspondent_table
is non-zero are tables in auxilary table list of multi-delete and these
tables are handled specially in mysql_multi_delete_prepare().
New more SP-locking friendly approach to handling locks in multi-update.
Now we mark all tables of multi-update as needing write lock at parsing
stage and if possible downgrade lock at execution stage (For its work
SP-locking mechanism needs to know all lock types right after parsing
stage).
