Log Message:
Update ffmpeg3 and ffplay3 to 3.1.1

Changelog:
version 3.1.1:
- doc/APIchanges: document the lavu/lavf field moves
- avformat/avformat: Move new field to the end of AVStream
- avformat/utils: update deprecated AVStream->codec when the context is updated
- avutil/frame: Move new field to the end of AVFrame
- libavcodec/exr : fix decoding piz float file.
- avformat/mov: Check sample size
- lavfi: Move new field to the end of AVFilterContext
- lavfi: Move new field to the end of AVFilterLink
- ffplay: Fix usage of private lavfi API
- lavc/mediacodecdec_h264: add missing NAL headers to SPS/PPS buffers
- lavc/pnm_parser: disable parsing for text based PNMs

version 3.1:
- DXVA2-accelerated HEVC Main10 decoding
- fieldhint filter
- loop video filter and aloop audio filter
- Bob Weaver deinterlacing filter
- firequalizer filter
- datascope filter
- bench and abench filters
- ciescope filter
- protocol blacklisting API
- MediaCodec H264 decoding
- VC-2 HQ RTP payload format (draft v1) depacketizer and packetizer
- VP9 RTP payload format (draft v2) packetizer
- AudioToolbox audio decoders
- AudioToolbox audio encoders
- coreimage filter (GPU based image filtering on OSX)
- libdcadec removed
- bitstream filter for extracting DTS core
- ADPCM IMA DAT4 decoder
- musx demuxer
- aix demuxer
- remap filter
- hash and framehash muxers
- colorspace filter
- hdcd filter
- readvitc filter
- VAAPI-accelerated format conversion and scaling
- libnpp/CUDA-accelerated format conversion and scaling
- Duck TrueMotion 2.0 Real Time decoder
- Wideband Single-bit Data (WSD) demuxer
- VAAPI-accelerated H.264/HEVC/MJPEG encoding
- DTS Express (LBR) decoder
- Generic OpenMAX IL encoder with support for Raspberry Pi
- IFF ANIM demuxer & decoder
- Direct Stream Transfer (DST) decoder
- loudnorm filter
- MTAF demuxer and decoder
- MagicYUV decoder
- OpenExr improvements (tile data and B44/B44A support)
- BitJazz SheerVideo decoder
- CUDA CUVID H264/HEVC decoder
- 10-bit depth support in native utvideo decoder
- libutvideo wrapper removed
- YUY2 Lossless Codec decoder
- VideoToolbox H.264 encoder