Backport of subquery optimizations to 5.3.

There are still test failures because of:
- Wrong query results in outer join + semi join
- EXPLAIN output differences

sql/item_func.h

@@ -117,6 +117,7 @@ public:
   // Constructor used for Item_cond_and/or (see Item comment)
   Item_func(THD *thd, Item_func *item);
   bool fix_fields(THD *, Item **ref);
+  void fix_after_pullout(st_select_lex *new_parent, Item **ref);
   table_map used_tables() const;
   table_map not_null_tables() const;
   void update_used_tables();