sgsn: Remove warnings

Remove warnings related to the SGSN specific code.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/tests/subscr/subscr_test.c b/openbsc/tests/subscr/subscr_test.c
index fdd5cd8..277fc88 100644
--- a/openbsc/tests/subscr/subscr_test.c
+++ b/openbsc/tests/subscr/subscr_test.c
@@ -35,7 +35,6 @@
 
 static void test_subscr(void)
 {
-	int rc;
 	struct gsm_subscriber *subscr;
 	const char *imsi = "1234567890";
 
@@ -88,8 +87,6 @@
 
 int main()
 {
-	char scratch_str[256];
-
 	printf("Testing subscriber core code.\n");
 	osmo_init_logging(&log_info);
 	log_set_print_filename(osmo_stderr_target, 0);