Enable support of access to tables from triggers. Thus fix bug #8406 "Triggers

crash if referencing a table" and several other related bugs.
Fix for bug #11834 "Re-execution of prepared statement with dropped function
crashes server." which was spotted during work on previous bugs.

Also couple of nice cleanups:
- Replaced two separate hashes for stored routines used by statement with one.
- Now instead of doing one pass through all routines used in statement for
  caching them and then doing another pass for adding their tables to table
  list, we do only one pass during which do both things.

sql/sql_trigger.h

@@ -1,3 +1,20 @@
+/* Copyright (C) 2004-2005 MySQL AB
+
+   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 Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA */
+
+
 /*
   This class holds all information about triggers of table.
 
@@ -28,6 +45,14 @@ class Table_triggers_list: public Sql_alloc
     used in CREATE/DROP TRIGGER for looking up trigger by name.
   */
   List<LEX_STRING>  names_list;
+  /*
+    Key representing triggers for this table in set of all stored
+    routines used by statement.
+    TODO: We won't need this member once triggers namespace will be
+    database-wide instead of table-wide because then we will be able
+    to use key based on sp_name as for other stored routines.
+  */
+  LEX_STRING        sroutines_key;
 
 public:
   /*
@@ -112,6 +137,8 @@ public:
   }
 
   friend class Item_trigger_field;
+  friend void sp_cache_routines_and_add_tables_for_triggers(THD *thd, LEX *lex,
+                Table_triggers_list *triggers);
 
 private:
   bool prepare_record1_accessors(TABLE *table);