nat: Make the MSC configurable.
diff --git a/openbsc/include/openbsc/bsc_nat.h b/openbsc/include/openbsc/bsc_nat.h
index 3754f25..54a13e2 100644
--- a/openbsc/include/openbsc/bsc_nat.h
+++ b/openbsc/include/openbsc/bsc_nat.h
@@ -205,6 +205,7 @@
 
 	/* msc things */
 	char *msc_ip;
+	int msc_port;
 	int first_contact;
 
 	struct bsc_endpoint *bsc_endpoints;