* df.c (df_visit_next_rts): New function.
(df_visit_next): Renamed to df_visit_next_rc
(df_analyse_1): Allocate/compute/free rts_order as well.
(df_rd_global_compute): Use df_visit_next_rc instead of
df_visit_next.
(df_ru_global_compute): Use df_visit_next_rts instead of
df_visit_next.
* flow.c (flow_reverse_top_sort_order_compute): New function.