refs: convert resolve_gitlink_ref to struct object_id

Convert the declaration and definition of resolve_gitlink_ref to use
struct object_id and apply the following semantic patch:

@@
expression E1, E2, E3;
@@
- resolve_gitlink_ref(E1, E2, E3.hash)
+ resolve_gitlink_ref(E1, E2, &E3)

@@
expression E1, E2, E3;
@@
- resolve_gitlink_ref(E1, E2, E3->hash)
+ resolve_gitlink_ref(E1, E2, E3)

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff-lib.c

@@ -50,7 +50,7 @@ static int check_removed(const struct cache_entry *ce, struct stat *st)
 		 * a directory --- the blob was removed!
 		 */
 		if (!S_ISGITLINK(ce->ce_mode) &&
-		    resolve_gitlink_ref(ce->name, "HEAD", sub.hash))
+		    resolve_gitlink_ref(ce->name, "HEAD", &sub))
 			return 1;
 	}
 	return 0;