tsdemux: reset the state of the stream when flushing

We need to reset the stream on a flush or else old packets could be added to the
list and leak.

gst/mpegtsdemux/tsdemux.c

@@ -1023,6 +1023,7 @@ gst_ts_demux_stream_flush (TSDemuxStream * stream)
     stream->currentlist = NULL;
   }
 
+  stream->state = PENDING_PACKET_EMPTY;
   stream->expected_size = 0;
   stream->current_size = 0;
   stream->need_newsegment = TRUE;