gbproxy: Add test for NSEI and NSVCI changes

This checks the behavior of the gbproxy when the BSS peer changes the
NSEI and the NSVCI. It also tests BVC_RESET and other UNITDATA
messages after these changes between BSS and SGSN and vice versa (via
the gbproxy).

Ticket: OW#874
Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c
index 6f7d1c3..f008b3e 100644
--- a/openbsc/src/gprs/gb_proxy.c
+++ b/openbsc/src/gprs/gb_proxy.c
@@ -881,6 +881,17 @@
 	return 0;
 }
 
+void gbprox_reset()
+{
+	struct gbprox_peer *peer, *tmp;
+
+	llist_for_each_entry_safe(peer, tmp, &gbprox_bts_peers, list)
+		peer_free(peer);
+
+	rate_ctr_group_free(global_ctrg);
+	global_ctrg = NULL;
+}
+
 static int gbprox_cleanup_peers(uint16_t nsei, uint16_t bvci)
 {
 	int counter = 0;