Log gtpc_delete_session_request_hdl

When a eNodeB detects a radio error (for instance a cell phone switching
to plane mode), the MME or AMF emits a delete session request to the SGW
and then the SGW emits a GTPc delete session request to the PGW
(gtp-guard). Let's log this event.

src/gtp_router_hdl.c

@@ -1109,6 +1109,8 @@ gtpc_delete_session_request_hdl(gtp_server_worker_t *w, struct sockaddr_storage
 		goto end;
 	}
 
+	log_message(LOG_INFO, "Delete-Session-Req:={F-TEID:0x%.8x}", ntohl(teid->peer_teid->id));
+
 	msg_ie = gtp_msg_ie_get(msg, GTP_IE_F_TEID_TYPE);
 	if (!msg_ie) {
 		log_message(LOG_INFO, "%s(): no F_TEID IE present. ignoring..."