notes: mark unused callback parameters

for_each_note() requires a callback, but not all callbacks need all of
the parameters. Likewise, init_notes() takes a callback to implement the
"combine" strategy, but the "ignore" variant obviously doesn't look at
its arguments at all. Mark unused parameters as appropriate to silence
compiler warnings.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/notes.c b/notes.c
index f2805d5..20af123 100644
--- a/notes.c
+++ b/notes.c
@@ -752,7 +752,7 @@ static int write_each_non_note_until(const char *note_path,
 	return 0;
 }
 
-static int write_each_note(const struct object_id *object_oid,
+static int write_each_note(const struct object_id *object_oid UNUSED,
 		const struct object_id *note_oid, char *note_path,
 		void *cb_data)
 {
@@ -780,8 +780,9 @@ struct note_delete_list {
 };
 
 static int prune_notes_helper(const struct object_id *object_oid,
-		const struct object_id *note_oid, char *note_path,
-		void *cb_data)
+			      const struct object_id *note_oid UNUSED,
+			      char *note_path UNUSED,
+			      void *cb_data)
 {
 	struct note_delete_list **l = (struct note_delete_list **) cb_data;
 	struct note_delete_list *n;
@@ -848,8 +849,8 @@ int combine_notes_overwrite(struct object_id *cur_oid,
 	return 0;
 }
 
-int combine_notes_ignore(struct object_id *cur_oid,
-			 const struct object_id *new_oid)
+int combine_notes_ignore(struct object_id *cur_oid UNUSED,
+			 const struct object_id *new_oid UNUSED)
 {
 	return 0;
 }