diffcore-pickaxe: mark unused parameters in pickaxe functions

We have a virtual pickaxe_fn for handling -G versus -S pickaxe options.
They need to take the same set of parameters, but of course they care
about different ones (e.g., a regex -G will never use a kwset).

Mark the unused ones to appease -Wunused-parameter.

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

diffcore-pickaxe.c

@@ -38,7 +38,7 @@ static int diffgrep_consume(void *priv, char *line, unsigned long len)
 
 static int diff_grep(mmfile_t *one, mmfile_t *two,
 		     struct diff_options *o,
-		     regex_t *regexp, kwset_t kws)
+		     regex_t *regexp, kwset_t kws UNUSED)
 {
 	struct diffgrep_cb ecbdata;
 	xpparam_t xpp;
@@ -114,7 +114,7 @@ static unsigned int contains(mmfile_t *mf, regex_t *regexp, kwset_t kws,
 }
 
 static int has_changes(mmfile_t *one, mmfile_t *two,
-		       struct diff_options *o,
+		       struct diff_options *o UNUSED,
 		       regex_t *regexp, kwset_t kws)
 {
 	unsigned int c1 = one ? contains(one, regexp, kws, 0) : 0;