hashmap: mark unused callback parameters

Hashmap comparison functions must conform to a particular callback
interface, but many don't use all of their parameters. Especially the
void cmp_data pointer, but some do not use keydata either (because they
can easily form a full struct to pass when doing lookups). Let's mark
these to make -Wunused-parameter happy.

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

bloom.c

@@ -163,10 +163,10 @@ void init_bloom_filters(void)
 	init_bloom_filter_slab(&bloom_filters);
 }
 
-static int pathmap_cmp(const void *hashmap_cmp_fn_data,
+static int pathmap_cmp(const void *UNUSED(hashmap_cmp_fn_data),
 		       const struct hashmap_entry *eptr,
 		       const struct hashmap_entry *entry_or_key,
-		       const void *keydata)
+		       const void *UNUSED(keydata))
 {
 	const struct pathmap_hash_entry *e1, *e2;