anchor.diff:      ++ optionals pulseSupport [ libpulseaudio ]
       ++ optionals sdlSupport [ SDL ]
       ++ optionals vncSupport [ libjpeg libpng ]
  -    ++ optionals spiceSupport [ spice_protocol spice usbredir ]
  +    ++ optionals spiceSupport [ spice_protocol spice ]
  +    ++ optionals usbredirSupport [ usbredir ]
       ++ optionals stdenv.isLinux [ alsaLib libaio libcap_ng libcap attr ];
   
     enableParallelBuilding = true;
  
positive.code:     ++ optional numaSupport "--enable-numa"
      ++ optional seccompSupport "--enable-seccomp"
      ++ optional spiceSupport "--enable-spice"
      ++ optional x86Only "--target-list=i386-softmmu,x86_64-softmmu"
      ++ optional stdenv.isDarwin "--enable-cocoa"
      ++ optional stdenv.isLinux "--enable-linux-aio";
  
negative.code: , pulseSupport ? !stdenv.isDarwin, libpulseaudio
  , sdlSupport ? !stdenv.isDarwin, SDL
  , vncSupport ? true, libjpeg, libpng
  , spiceSupport ? !stdenv.isDarwin, spice, spice_protocol
  , usbredirSupport ? spiceSupport, usbredir
  , x86Only ? false
  , nixosTestRunner ? false
  }:
  