Log Message:
libvpx: update to 1.7.0.

2017-01-04 v1.7.0 "Mandarin Duck"
  This release focused on high bit depth performance (10/12 bit) and vp9
  encoding improvements.

  - Upgrading:
    This release is ABI incompatible due to new vp9 encoder features.

    Frame parallel decoding for vp9 has been removed.

  - Enhancements:
    vp9 encoding supports additional threads with --row-mt. This can be greater
    than the number of tiles.

    Two new vp9 encoder options have been added:
      --corpus-complexity
      --tune-content=film

    Additional tooling for respecting the vp9 "level" profiles has \ 
been added.

  - Bug fixes:
    A variety of fuzzing issues.
    vp8 threading fix for ARM.
    Codec control VP9_SET_SKIP_LOOP_FILTER fixed.
    Reject invalid multi resolution configurations.