Subquery optimizations: non-semijoin materialization

- Backport into Maria DB 5.3, part 1

sql/opt_range.cc

@@ -5493,7 +5493,7 @@ static SEL_TREE *get_mm_tree(RANGE_OPT_PARAM *param,COND *cond)
     DBUG_RETURN(tree);
   }
   /* Here when simple cond */
-  if (cond->const_item())
+  if (cond->const_item() && !cond->is_expensive())
   {
     /*
       During the cond->val_int() evaluation we can come across a subselect