anchor.diff:      libvorbis
       libvpx
       libwebp
  -    mesa_noglu
       mfx-dispatcher
       nvidia-cuda-toolkit
       nvidia-drivers
       openal
  +    opengl-dummy
       openh264
       openjpeg
       opus
  
positive.code: , libxcbxfixesExtlib ? true
  , libxcbshapeExtlib ? true
  , libzimg ? null
  , mesa_noglu
  , mfx-dispatcher
  , mmal ? null
  , nvenc ? false
  
negative.code:     "--${boolEn (openal != null)}-openal"
      #"--${boolEn (opencl != null)}-opencl"
      /**/"--disable-opencl"
      "--${boolEn (opengl-dummy != null && opengl-dummy.glx)}-opengl"
      "--${boolEn (openssl != null)}-openssl"
      "--disable-schannel"  # windows
      "--${boolEn (SDL_2 != null)}-sdl"
  