Fix incorrect frame rate detection of some videos with variable frame rate.

Use FFMPEG's r_frame_rate, if it as valid, as a video stream frame rate, otherwise use avg_frame_rate.
Also remove CDVDStreamInfo.rfpsscale, CDVDStreamInfo.rfpsrate, CDemuxStreamVideo.irFpsScale and CDemuxStreamVideo.irFpsRate,
they are not needed anymore.
[aml] Always use the SYNC_OUTSIDE decoder flag for most smooth playback of H264 video