nitb: Add a test for "show network" in the python testsuite.

Make sure that bsc_gsmnet->bsc_data->rf_ctrl is initialized for
NITB. In commit a9fae1ae66df57f76a0aedbd0b56228959d37d56 the
conditions for the rf_ctrl was removed but it was still needed
for the NITB.

Fixes regression from:
a9fae1ae66df57f76a0aedbd0b56228959d37d56
bsc: rf_ctrl will always be created, remove the NULL checks
diff --git a/openbsc/src/osmo-nitb/bsc_hack.c b/openbsc/src/osmo-nitb/bsc_hack.c
index d746bf1..67c65ce 100644
--- a/openbsc/src/osmo-nitb/bsc_hack.c
+++ b/openbsc/src/osmo-nitb/bsc_hack.c
@@ -38,6 +38,7 @@
 #include <osmocom/core/talloc.h>
 #include <openbsc/signal.h>
 #include <openbsc/osmo_msc.h>
+#include <openbsc/osmo_msc_data.h>
 #include <openbsc/sms_queue.h>
 #include <openbsc/vty.h>
 #include <openbsc/bss.h>
@@ -52,7 +53,6 @@
 
 /* MCC and MNC for the Location Area Identifier */
 struct gsm_network *bsc_gsmnet = 0;
-static struct osmo_bsc_rf *rf_ctrl;
 static const char *database_name = "hlr.sqlite3";
 static const char *config_file = "openbsc.cfg";
 static const char *rf_ctrl_name = NULL;
@@ -298,8 +298,8 @@
 	/* seed the PRNG */
 	srand(time(NULL));
 
-	rf_ctrl = osmo_bsc_rf_create(rf_ctrl_name, bsc_gsmnet);
-	if (!rf_ctrl) {
+	bsc_gsmnet->bsc_data->rf_ctrl = osmo_bsc_rf_create(rf_ctrl_name, bsc_gsmnet);
+	if (!bsc_gsmnet->bsc_data->rf_ctrl) {
 		fprintf(stderr, "Failed to create the RF service.\n");
 		exit(1);
 	}