stream_dvb: Enable streaming mode, activates cache.

This causes more constant reading from the DVB device,
and seems not to hurt the stream-controls.
As the device cache seems to fill up when not
reading from it for several seconds, reading
into the cache fixes desync-issues after
the initial analyzeduration of the demuxer.

stream/stream_dvb.c

@@ -901,6 +901,7 @@ static int dvb_open(stream_t *stream)
         stream->fill_buffer = dvb_streaming_read;
         stream->close = dvbin_close;
         stream->control = dvbin_stream_control;
+        stream->streaming = true;
 
         stream->demuxer = "lavf";
         stream->lavf_type = "mpegts";