reachable.hon commit t7800: fix tests when difftool uses --no-symlinks (3caf5a9)
   1#ifndef REACHEABLE_H
   2#define REACHEABLE_H
   3
   4struct progress;
   5extern void mark_reachable_objects(struct rev_info *revs, int mark_reflog, struct progress *);
   6
   7#endif