FTBFS from release tarball on windows

[ericLemanissier]

When downloading the release tarball on windows, the build fails with ..\src\va\meson.build:301:2: ERROR: File win32/va_win32.h does not exist.
Indeed, the win32 folder does not exist in https://github.com/intel/libva/releases/download/2.20.0/libva-2.20.0.tar.bz2. it does exist in https://github.com/intel/libva/archive/refs/tags/2.20.0.tar.gz

[eli-schwartz]

The autotools build doesn't include files which aren't used by it (like win32 codepaths) unless they are included as EXTRA_DIST -- and the win32 files aren't listed in EXTRA_DIST.

[eli-schwartz]

#791 would allow meson to create the dist tarballs instead of autotools. Meson has a different approach to ensuring file inclusion.

[XinfengZhang]

plan to remove bz2, and use github auto generated gz file, but it does is an issue.