refs: convert update_ref and refs_update_ref to use struct object_id

Convert update_ref, refs_update_ref, and write_pseudoref to use struct
object_id.  Update the existing callers as well.  Remove update_ref_oid,
as it is no longer needed.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/reset.c b/builtin/reset.c
index 5f3632e..d4003f7 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -266,12 +266,12 @@ static int reset_refs(const char *rev, const struct object_id *oid)
 	if (!get_oid("HEAD", &oid_orig)) {
 		orig = &oid_orig;
 		set_reflog_message(&msg, "updating ORIG_HEAD", NULL);
-		update_ref_oid(msg.buf, "ORIG_HEAD", orig, old_orig, 0,
+		update_ref(msg.buf, "ORIG_HEAD", orig, old_orig, 0,
 			   UPDATE_REFS_MSG_ON_ERR);
 	} else if (old_orig)
 		delete_ref(NULL, "ORIG_HEAD", old_orig, 0);
 	set_reflog_message(&msg, "updating HEAD", rev);
-	update_ref_status = update_ref_oid(msg.buf, "HEAD", oid, orig, 0,
+	update_ref_status = update_ref(msg.buf, "HEAD", oid, orig, 0,
 				       UPDATE_REFS_MSG_ON_ERR);
 	strbuf_release(&msg);
 	return update_ref_status;