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.cc

@@ -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 */
+
+
 #include "mysql_priv.h"
 #include "sp_head.h"
 #include "sql_trigger.h"
@@ -417,6 +434,18 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
 
       table->triggers= triggers;
 
+      /*
+        Construct key that will represent triggers for this table in the set
+        of routines used by statement.
+      */
+      triggers->sroutines_key.length= 1+strlen(db)+1+strlen(table_name)+1;
+      if (!(triggers->sroutines_key.str=
+              alloc_root(&table->mem_root, triggers->sroutines_key.length)))
+        DBUG_RETURN(1);
+      triggers->sroutines_key.str[0]= TYPE_ENUM_TRIGGER;
+      strmov(strmov(strmov(triggers->sroutines_key.str+1, db), "."),
+             table_name);
+
       /*
         TODO: This could be avoided if there is no triggers
               for UPDATE and DELETE.