main: display mgcp ip/port

osmo-mgw does not display the IP/Port on which it is listening for
MGCP commands. However, this information can be very helpful when
working with multiple MGCP instances on one machine.

- print IP/Port on which we listen for MGCP commands on startup

Change-Id: Idf5e8b6a7344c4ebaf9b89940456a496b2c23334

src/osmo-mgw/mgw_main.c

@@ -309,7 +309,8 @@ int main(int argc, char **argv)
 		return -1;
 	}
 
-	LOGP(DLMGCP, LOGL_NOTICE, "Configured for MGCP.\n");
+	LOGP(DLMGCP, LOGL_NOTICE, "Configured for MGCP, listen on %s:%u\n",
+	     cfg->source_addr, cfg->source_port);
 
 	/* initialisation */
 	srand(time(NULL));