revision: remove declaration of path_name()

The definition of path_name() was removed by 2824e1841 (list-objects:
pass full pathname to callbacks); remove its declaration as well.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

revision.h

@@ -256,8 +256,6 @@ extern void put_revision_mark(const struct rev_info *revs,
 extern void mark_parents_uninteresting(struct commit *commit);
 extern void mark_tree_uninteresting(struct tree *tree);
 
-char *path_name(struct strbuf *path, const char *name);
-
 extern void show_object_with_name(FILE *, struct object *, const char *);
 
 extern void add_pending_object(struct rev_info *revs,