rtsp: suppress a incompatible pointer types warning

libavformat/rtsp.c

@@ -726,8 +726,8 @@ int ff_rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
         s->ctx_flags |= AVFMTCTX_NOHEADER;
 
     if (s->oformat && CONFIG_RTSP_MUXER) {
-        int ret = ff_rtp_chain_mux_open(&rtsp_st->transport_priv, s, st,
-                                        rtsp_st->rtp_handle,
+        int ret = ff_rtp_chain_mux_open((AVFormatContext **)&rtsp_st->transport_priv,
+                                        s, st, rtsp_st->rtp_handle,
                                         RTSP_TCP_MAX_PACKET_SIZE,
                                         rtsp_st->stream_index);
         /* Ownership of rtp_handle is passed to the rtp mux context */