* rtl.h (rebuild_jump_labels): Declare.
* jump.c (jump_optimize_1): Renamed from jump_optimize. Make static.
Add new argument MARK_LABELS_ONLY. Quit after mark_all_labels if
requested.
(jump_optimize, rebuild_jump_labels): New wrapper functions for
jump_optimize_1.
* toplev.c (rest_of_compilation): Use rebuild_jump_labels instead of
running the entire jump optimizer.