anchor.diff:      ++ optional hostCpuOnly "--target-list=${hostCpuTargets}"
       ++ optional stdenv.isDarwin "--enable-cocoa"
       ++ optional stdenv.isLinux "--enable-linux-aio"
  +    ++ optional gtkSupport "--enable-gtk"
       ++ optional xenSupport "--enable-xen"
       ++ optional openGLSupport "--enable-opengl"
       ++ optional virglSupport "--enable-virglrenderer";
  
positive.code: , seccompSupport ? stdenv.isLinux, libseccomp
  , pulseSupport ? !stdenv.isDarwin, libpulseaudio
  , sdlSupport ? !stdenv.isDarwin, SDL2
  , vncSupport ? true, libjpeg, libpng
  , spiceSupport ? !stdenv.isDarwin, spice, spice-protocol
  , usbredirSupport ? spiceSupport, usbredir
  
negative.code:     ++ optionals numaSupport [ numactl ]
      ++ optionals pulseSupport [ libpulseaudio ]
      ++ optionals sdlSupport [ SDL2 ]
      ++ optionals gtkSupport [ gtk3 gettext gnome3.vte ]
      ++ optionals vncSupport [ libjpeg libpng ]
      ++ optionals spiceSupport [ spice-protocol spice ]
      ++ optionals usbredirSupport [ usbredir ]
  