Backport of:

----------------------------------------------------------
revno: 2617.69.24
committer: Konstantin Osipov <kostja@sun.com>
branch nick: 5.4-42546
timestamp: Fri 2009-08-14 19:22:05 +0400
message:
  A pre-requisite for a fix for Bug#42546 "Backup: RESTORE fails, thinking it
  finds an existing table"
  Back-port from WL 148 "Foreign keys" feature tree a patch
  that introduced Prelocking_strategy class -- a way to parameterize
  open_tables() behaviour, implemented by Dmitry Lenev.

(Part of WL#4284).

sql/sql_base.cc:
  Implement different prelocking strategies. Use an instance of
  prelocking_strategy in open_tables().
sql/sql_class.h:
  Add declarations for class Prelocking_strategy.
sql/sql_lex.h:
  Add a helper method to access last table of the global table list
  (lex->query_tables).
sql/sql_parse.cc:
  Use a special prelocking strategy when locking tables for LOCK TABLES.
sql/sql_table.cc:
  Use normal open_and_lock_tables_derived() in ALTER TABLE.
sql/sql_yacc.yy:
  Modify the grammar to not pollute the global table list with tables
  that should not be opened.

sql/sql_trigger.h

@@ -144,8 +144,10 @@ public:
   void mark_fields_used(trg_event_type event);
 
   friend class Item_trigger_field;
-  friend int sp_cache_routines_and_add_tables_for_triggers(THD *thd, LEX *lex,
-                                                            TABLE_LIST *table);
+
+  bool add_tables_and_routines_for_triggers(THD *thd,
+                                            Query_tables_list *prelocking_ctx,
+                                            TABLE_LIST *table_list);
 
 private:
   bool prepare_record1_accessors(TABLE *table);