Permit libortp to use the connect() syscall, enabling later getsockname()

If we bind a local socket to INADDR_ANY, then getsockname() will always
return 0.0.0.0 for the local IP address _unless_ the socket was
previously connected to a specific remote IP/port using connect().

This will have the side effect that we only accept RTP packets from the
one IP/port that we have connect()ed to, but that is actually
intentional and useful in our applications.
diff --git a/src/trau/osmo_ortp.c b/src/trau/osmo_ortp.c
index a9503ea..0e1e108 100644
--- a/src/trau/osmo_ortp.c
+++ b/src/trau/osmo_ortp.c
@@ -351,6 +351,11 @@
 {
 	int rc;
 
+	/* enable the use of connect() so later getsockname() will
+	 * actually return the IP address that was chosen for the local
+	 * sid of the connection */
+	rtp_session_set_connected_mode(rs->sess, 1);
+
 	rc = rtp_session_set_remote_addr(rs->sess, ip, port);
 	if (rc < 0)
 		return rc;