Fix bluray scene changes in HDMV navigation mode.

Bluray can include some significant video stream changes that our stream
change handling code cannot deal - especially VC1. By probing the file,
we ensure that all of the video codec parameters are found.

As noted in the code, if enabled by default this would probably help
with some other bugs/issues around stream changes.

mythtv/libs/libmythtv/avformatdecoder.cpp

@@ -1661,6 +1661,10 @@ int AvFormatDecoder::ScanStreams(bool novideo)
         RemoveAudioStreams();
     }
 
+    // TODO this could probably be used by default
+    if (ringBuffer && ringBuffer->IsBD())
+        av_find_stream_info(ic);
+
     for (uint i = 0; i < ic->nb_streams; i++)
     {
         AVCodecContext *enc = ic->streams[i]->codec;