WinCE: fix build of the RTP stream output

WSADuplicateSocket() doesn't exist, so just skip that bit of code...

modules/stream_out/rtcp.c

@@ -83,6 +83,9 @@ rtcp_sender_t *OpenRTCP (vlc_object_t *obj, int rtp_fd, int proto,
         /* RTP/RTCP mux: duplicate the socket */
 #ifndef WIN32
         fd = dup (rtp_fd);
+#elif defined(UNDER_CE)
+ #warning Muxed RTP/RTCP unimplemented!
+        fd = -1;
 #else
         WSAPROTOCOL_INFO info;
         WSADuplicateSocket (rtp_fd, GetCurrentProcessId (), &info);