Add a codec capable of decoding some formats of the RFC4175. For now
it's only capable of handling YCbCr-4:2:2 with 8-bit or 10-bit depth.

For 8-bit it's a simple pass-through, for 10-bit it depacks the stream
in the AV_PIX_FMT_YUV422P10 pixel format.
Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
Reviewed-by: Rostislav Pehlivanov <atomnuker@gmail.com>

* commit 'bf2f748f':
  configure: Use correct libm linker flag during math function checks
Merged-by: James Almer <jamrial@gmail.com>

* commit 'ce6f780b':
  configure: Add missing asyncts filter, movie filter, and output example deps
Merged-by: James Almer <jamrial@gmail.com>

* commit '04698d52':
  configure: Use correct variable name in libsnappy test
Merged-by: James Almer <jamrial@gmail.com>

* commit '30f0d1b9':
  configure: Remove old avisynth support leftover
Merged-by: James Almer <jamrial@gmail.com>

* commit '6a1ea4ec':
  arm: warn/error on movrelx usage problematic with PIC on ELF
Merged-by: James Almer <jamrial@gmail.com>

* commit '5bcc6f76':
  configure: Disable warning C4703 with MSVC
Merged-by: James Almer <jamrial@gmail.com>

* commit 'bd9cd046':
  w32pthreads: Fix function pointer casts
Merged-by: James Almer <jamrial@gmail.com>

* commit '233d50b2':
  qt-faststart: Do not try to use fancy 64-bit seeking functions on mingw32ce
Merged-by: James Almer <jamrial@gmail.com>

* commit '537b5b77':
  rtmpdh: Do global initialization before running the test
Merged-by: James Almer <jamrial@gmail.com>

* commit '2f99117f':
  aarch64: vp9itxfm: Don't repeatedly set x9 when nothing overwrites it

This commit is a noop, see 37cb224eMerged-by: James Almer <jamrial@gmail.com>

* commit '2dbe2aa2':
  rdt: Convert to the new bitstream reader
  ogg: Convert to the new bitstream reader
  mpegts: Convert to the new bitstream reader
  xsubdec: Convert to the new bitstream reader
  xan: Convert to the new bitstream reader
  wnv1: Convert to the new bitstream reader
  vima: Convert to the new bitstream reader
  vble: Convert to the new bitstream reader
  utvideodec: Convert to the new bitstream reader
  twinvq: Convert to the new bitstream reader
  tscc2: Convert to the new bitstream reader
  truespeech: Convert to the new bitstream reader
  tiertex: Convert to the new bitstream reader
  truemotion2: Convert to the new bitstream reader
  svq1dec: Convert to the new bitstream reader
  smacker: Convert to the new bitstream reader
  sipr: Convert to the new bitstream reader
  rtjpeg: Convert to the new bitstream reader
  ra288: Convert to the new bitstream reader
  ra144: Convert to the new bitstream reader

This merge is a noop, see
http://ffmpeg.org/pipermail/ffmpeg-devel/2017-April/209609.htmlMerged-by: James Almer <jamrial@gmail.com>

* commit '79566ec8':
  arm: vp9itxfm: Rename a macro parameter to fit better

This commit is a noop, see f69dd26dMerged-by: James Almer <jamrial@gmail.com>

* commit '721bc375':
  arm/aarch64: vp9itxfm: Fix indentation of macro arguments

This commit is a noop.
Merged-by: James Almer <jamrial@gmail.com>

* commit '06fec74c':
  checkasm: vp9dsp: benchmark all sub-IDCTs (but not WHT or ADST).

This commit is a noop, see 1c8fbd7bMerged-by: James Almer <jamrial@gmail.com>

* commit 'effc1430':
  Revert "checkasm: vp9dsp: Benchmark the dc-only version of idct_idct separately"
Merged-by: James Almer <jamrial@gmail.com>

* commit '12ab667e':
  matroska: use av_stream_add_side_data() for stereo3d side data
  mov: Use av_stream_add_side_data() for displaymatrix side data
  utils: Add av_stream_add_side_data()

This is a noop, see
2ab50647
77f033eb
2343f23eMerged-by: James Almer <jamrial@gmail.com>

* commit '286ab878':
  fate.sh: Allow setting other make flags for running tests
Merged-by: James Almer <jamrial@gmail.com>

* commit 'aa498c31':
  avpacket: fix leak on realloc in av_packet_add_side_data()

This commit is a noop, see 574929d8Merged-by: James Almer <jamrial@gmail.com>

* commit 'c7ab0eb3':
  examples/decode_video: allocate the packet dynamically
Merged-by: James Almer <jamrial@gmail.com>

* commit '728ea23c':
  examples/decode_video: switch to the new decoding API
Merged-by: James Almer <jamrial@gmail.com>

* commit 'f78d360b':
  examples/decode_video: use a parser for splitting the input
Merged-by: James Almer <jamrial@gmail.com>

* commit '59ab9e8b':
  examples/encode_video: allocate the packet dynamically
Merged-by: Clément Bœsch <cboesch@gopro.com>

* commit '5f102a95':
  examples/encode_video: switch to the new encoding API
Merged-by: Clément Bœsch <cboesch@gopro.com>

* commit 'fee0f1de':
  examples/decode_audio: flush the decoder
Merged-by: Clément Bœsch <cboesch@gopro.com>

* commit '9a38184a':
  examples/decode_audio: allocate the packet dynamically
Merged-by: Clément Bœsch <cboesch@gopro.com>

* commit '45a1ce2f':
  examples/decode_audio: handle planar audio now produced by the MP2 decoder

This commit is a noop, we use a simpler and more generic method to write
the samples.
Merged-by: Clément Bœsch <cboesch@gopro.com>

* commit '3d66717f':
  examples/decode_audio: use the new audio decoding API
Merged-by: Clément Bœsch <cboesch@gopro.com>

* commit '0946c754':
  examples/decode_audio: use a parser for splitting the input
Merged-by: Clément Bœsch <cboesch@gopro.com>

Not sure if it behaves ideally in presence of decoding errors.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>