diff: drop options parameter from diffcore_fix_diff_index()

The sole purpose of this function is to fix the sorting order of the
queued diff entries. It doesn't need to know about any diff options, so
we can drop the unused parameter.

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

diff.c

@@ -6224,7 +6224,7 @@ static int diffnamecmp(const void *a_, const void *b_)
 	return strcmp(name_a, name_b);
 }
 
-void diffcore_fix_diff_index(struct diff_options *options)
+void diffcore_fix_diff_index(void)
 {
 	struct diff_queue_struct *q = &diff_queued_diff;
 	QSORT(q->queue, q->nr, diffnamecmp);