Initialize thd->no_trans_update

(Fixes valgrind warnings)

sql/sql_class.cc

@@ -333,6 +333,7 @@ void THD::init(void)
   if (variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES)
     server_status|= SERVER_STATUS_NO_BACKSLASH_ESCAPES;
   options= thd_startup_options;
+  no_trans_update.stmt= no_trans_update.all= FALSE;
   open_options=ha_open_options;
   update_lock_default= (variables.low_priority_updates ?
 			TL_WRITE_LOW_PRIORITY :