Update ffmpeg3 and ffplay3 to 3.1.3.

version 3.1.3:
- examples/demuxing_decoding: convert to codecpar
- avcodec/exr: Check tile positions
- avcodec/aacenc: Tighter input checks
- avformat/wtvdec: Check pointer before use
- libavcodec/wmalosslessdec: Check the remaining bits
- avcodec/adpcm: Fix adpcm_ima_wav padding
- avcodec/svq3: fix slice size check
- avcodec/diracdec: Check numx/y
- avcodec/h2645_parse: fix nal size
- avcodec/h2645_parse: Use get_nalsize() in ff_h2645_packet_split()
- h2645_parse: only read avc length code at the correct position
- h2645_parse: don't overread AnnexB NALs within an avc stream
- avcodec/h264_parser: Factor get_avc_nalsize() out
- avcodec/cfhd: Increase minimum band dimension to 3
- avcodec/indeo2: check ctab
- avformat/swfdec: Fix inflate() error code check
- avcodec/rawdec: Fix bits_per_coded_sample checks
- vcodec/h2645_parse: Clear buffer padding
- avcodec/h2645: Fix NAL unit padding
- avfilter/drawutils: Fix single plane with alpha
- cmdutils: check for SetDllDirectory() availability

(wiz)