Dear maintainers,

As part of an investigation to establish the feasibility of moving 32-bit
archs to 64-bit time_t, I am running an analysis of all header files in the
archive to determine which libraries' ABIs are affected.  This requires the
headers in question to be compilable.

libavcodec-dev ships header files which have includes that are not sanely
satisfiable in Debian.  (They are Windows-specific D3D headers, only
available from wine; but referencing the wine implementation doesn't seem
sane either.) For my purposes, I've worked around these unusable headers by
adding quirks to my scripts, but it seems worth reporting as a bug that
headers are being shipped that aren't usable.

- libavcodec/d3d11va.h, which #includes d3d11.h
- libavcodec/dxva2.h, which #includes d3d9.h
- libavcodec/qsv.h depends on mfx/mfxvideo.h from libmfx-dev, which is
  amd64-only
- libavcodec/vdpau.h depends on vdpau/vdpau.h from libvdpau-dev
- libavcodec/videotoolbox.h depends on VideoToolbox/VideoToolbox.h, which
  does not exist in Debian