g10: Stop compiler warning for t-stutter.

* g10/t-stutter.c (do_test): Refer current_test_group_failed.

--

Since this test does not follow the framework of TEST/TEST_P/ABORT,
the variable is not used.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

g10/t-stutter.c

@@ -381,6 +381,7 @@ do_test (int argc, char *argv[])
   byte *raw_data;
   int raw_data_len;
 
+  (void)current_test_group_failed;
   for (i = 1; i < argc; i ++)
     {
       if (strcmp (argv[i], "--debug") == 0)