Bug#18964 "return 0 instead of DBUG_RETURN(0) in sql_base.cc::open_table()"

fixlet corrects return to DBUG_RETURN to restore the balance.

sql/sql_base.cc

@@ -1103,7 +1103,7 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root,
 
   /* an open table operation needs a lot of the stack space */
   if (check_stack_overrun(thd, STACK_MIN_SIZE_FOR_OPEN, (char *)&alias))
-    return 0;
+    DBUG_RETURN(0);
 
   if (thd->killed)
     DBUG_RETURN(0);