git: update to v2.5.0

Update to git version v2.5.0.

* Upstream commit 5455ee0573a22bb793a7083d593ae1ace909cd4c (Merge branch
  'bc/object-id') changed API:

  for_each_ref() callback functions were taught to name the objects
  not with "unsigned char sha1[20]" but with "struct object_id".

* Upstream commit dcf692625ac569fefbe52269061230f4fde10e47 (path.c: make
  get_pathname() call sites return const char *)

Signed-off-by: Christian Hesse <mail@eworm.de>

ui-log.c

@@ -249,11 +249,11 @@ static void print_commit(struct commit *commit, struct rev_info *revs)
 
 static const char *disambiguate_ref(const char *ref, int *must_free_result)
 {
-	unsigned char sha1[20];
+	struct object_id oid;
 	struct strbuf longref = STRBUF_INIT;
 
 	strbuf_addf(&longref, "refs/heads/%s", ref);
-	if (get_sha1(longref.buf, sha1) == 0) {
+	if (get_sha1(longref.buf, oid.hash) == 0) {
 		*must_free_result = 1;
 		return strbuf_detach(&longref, NULL);
 	}