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>

sha1_file.c

@@ -1841,7 +1841,7 @@ int index_path(struct object_id *oid, const char *path, struct stat *st, unsigne
 		strbuf_release(&sb);
 		break;
 	case S_IFDIR:
-		return resolve_gitlink_ref(path, "HEAD", oid->hash);
+		return resolve_gitlink_ref(path, "HEAD", oid);
 	default:
 		return error("%s: unsupported file type", path);
 	}