Provide many intel-qsv enhancements based on official ffmpeg-3.4.1:
- Add MJPEG decoding support
- Add MJPEG encoding support
- Add single/multiple input(s) overlay filter
- Enable hevc encoding on Linux
- HEVC/VP8/VC1/MPEG2 decoding conformance improvement
- Add deinterlace modes setting
- Add more h264/hevc encoding options
- Add FATE for H264 and HEVC decoders
- Fix vp8 decoding memory leak issue
- Fix hwupload failure issues
- Add RGB32 format support
- Improve performance for vpp bypass case
- Disable AVBR since it is not supported on Linux
- Load HEVC decoding/encoding hw plugins by default on Linux