Don't depend on C99 features.

* src/conflicts.c (conflicts_update_state_numbers): Fix for-loop.
* src/lalr.c (lalr_update_state_numbers): Fix for-loop.
* src/reader.c (check_and_convert_grammar): Fix for-loop.
* src/state.c (state_mark_reachable_states): Fix for-loop.
(state_remove_unreachable_states): Fix for-loop.

Don't widen struct state with member reachable just to temporarily
record reachability.  Instead, use a local bitset.
* src/state.h (struct state): Remove member.
* src/state.c (state_new): Don't initialize it.
(state_mark_reachable_states): Rename to...
(state_record_reachable_states): ... this, and use bitset.
(state_remove_unreachable_states): Use bitset.

src/state.h

@@ -209,11 +209,6 @@ struct state
      a human readable description of the resolution.  */
   const char *solved_conflicts;
 
-  /* Conflict resolution sometimes makes states unreachable.  Initialized to 0
-     in state_new and then used by state_remove_unreachable_states after
-     conflicts_solve.  */
-  bool reachable;
-
   /* Its items.  Must be last, since ITEMS can be arbitrarily large.
      */
   size_t nitems;