builtin/notes: convert to struct object_id

Convert most of the static functions to use struct object_id.  In
addition, convert copy_notes_for_rewrite and its callers.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/notes-utils.c b/notes-utils.c
index 325ff3d..7d7c22b 100644
--- a/notes-utils.c
+++ b/notes-utils.c
@@ -155,12 +155,12 @@ struct notes_rewrite_cfg *init_copy_notes_for_rewrite(const char *cmd)
 }
 
 int copy_note_for_rewrite(struct notes_rewrite_cfg *c,
-			  const unsigned char *from_obj, const unsigned char *to_obj)
+			  const struct object_id *from_obj, const struct object_id *to_obj)
 {
 	int ret = 0;
 	int i;
 	for (i = 0; c->trees[i]; i++)
-		ret = copy_note(c->trees[i], from_obj, to_obj, 1, c->combine) || ret;
+		ret = copy_note(c->trees[i], from_obj->hash, to_obj->hash, 1, c->combine) || ret;
 	return ret;
 }