grep: support -h (no header) with --count

Suppress printing the header (filename) with -h even if in -c/--count
mode.  GNU grep and OpenBSD's grep do the same.
Signed-off-by: NRene Scharfe <l.s.r@web.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

grep.c

@@ -1562,8 +1562,11 @@ static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int colle
 	 */
 	if (opt->count && count) {
 		char buf[32];
-		output_color(opt, gs->name, strlen(gs->name), opt->color_filename);
-		output_sep(opt, ':');
+		if (opt->pathname) {
+			output_color(opt, gs->name, strlen(gs->name),
+				     opt->color_filename);
+			output_sep(opt, ':');
+		}
 		snprintf(buf, sizeof(buf), "%u\n", count);
 		opt->output(opt, buf, strlen(buf));
 		return 1;

t/t7810-grep.sh

@@ -328,6 +328,18 @@ do
 			grep "a+b*c" $H ab >actual &&
 		test_cmp expected actual
 	'
+
+	test_expect_success "grep --count $L" '
+		echo ${HC}ab:3 >expected &&
+		git grep --count -e b $H -- ab >actual &&
+		test_cmp expected actual
+	'
+
+	test_expect_success "grep --count -h $L" '
+		echo 3 >expected &&
+		git grep --count -h -e b $H -- ab >actual &&
+		test_cmp expected actual
+	'
 done
 
 cat >expected <<EOF