libgb: Use library SS_L_NS instead lf local SS_NS

which removes some further dependencies of libgb to openbsc internal
code and data.
diff --git a/openbsc/include/osmocom/gprs/gprs_ns.h b/openbsc/include/osmocom/gprs/gprs_ns.h
index cfc2e90..ab4bd4e 100644
--- a/openbsc/include/osmocom/gprs/gprs_ns.h
+++ b/openbsc/include/osmocom/gprs/gprs_ns.h
@@ -203,7 +203,7 @@
 };
 
 /* Create a new NS protocol instance */
-struct gprs_ns_inst *gprs_ns_instantiate(gprs_ns_cb_t *cb);
+struct gprs_ns_inst *gprs_ns_instantiate(gprs_ns_cb_t *cb, void *ctx);
 
 /* Destroy a NS protocol instance */
 void gprs_ns_destroy(struct gprs_ns_inst *nsi);
@@ -246,6 +246,18 @@
 	return msgb_alloc_headroom(NS_ALLOC_SIZE, NS_ALLOC_HEADROOM, "GPRS/NS");
 }
 
+enum signal_ns {
+	S_NS_RESET,
+	S_NS_BLOCK,
+	S_NS_UNBLOCK,
+	S_NS_ALIVE_EXP,	/* Tns-alive expired more than N times */
+};
+
+struct ns_signal_data {
+	struct gprs_nsvc *nsvc;
+	uint8_t cause;
+};
+
 /*! }@ */
 
 #endif