worktree: mark unused parameters in noop repair callback

The noop repair callback unsurprisingly does not look at any of its
parameters. Mark them as unused to silence -Wunused-parameter.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

worktree.c

@@ -581,8 +581,10 @@ static void repair_gitfile(struct worktree *wt,
 	strbuf_release(&dotgit);
 }
 
-static void repair_noop(int iserr, const char *path, const char *msg,
-			void *cb_data)
+static void repair_noop(int iserr UNUSED,
+			const char *path UNUSED,
+			const char *msg UNUSED,
+			void *cb_data UNUSED)
 {
 	/* nothing */
 }