anchor.diff:    buildInputs = with xorg; [
       autoconf automake libtool intltool expat libxml2Python llvm
       libXfixes glproto dri2proto libX11 libXext libxcb libXt
  -    libffi wayland
  -  ] ++ optionals enableExtraFeatures [ /*libXvMC*/ libvdpau ]
  +    libffi wayland libvdpau
  +  ] ++ optionals enableExtraFeatures [ /*libXvMC*/ ]
       ++ optional stdenv.isLinux udev
       ++ optional enableR600LlvmCompiler libelf
       ;
  
positive.code:       "--enable-osmesa"
        "--enable-openvg" "--enable-gallium-egl" # not needed for EGL in Gallium, but OpenVG might be useful
        #"--enable-xvmc" # tests segfault with 9.1.{1,2,3}
        "--enable-vdpau"
        #"--enable-opencl" # ToDo: opencl seems to need libclc for clover
      ];
  
  
negative.code:     "--enable-gallium-llvm" "--with-llvm-shared-libs"
      "--enable-xa" # used in vmware driver
      "--enable-gles1" "--enable-gles2"
      "--enable-vdpau"
  
      "--with-dri-drivers=i965,r200,radeon"
      ("--with-gallium-drivers=i915,nouveau,r300,r600,svga,swrast"
  