anchor.diff:      ++ optionals usbredirSupport [ usbredir ]
       ++ optionals stdenv.isLinux [ alsaLib libaio libcap_ng libcap attr ]
       ++ optionals xenSupport [ xen ]
  +    ++ optionals cephSupport [ ceph ]
       ++ optionals openGLSupport [ mesa_noglu epoxy libdrm ]
       ++ optionals virglSupport [ virglrenderer ]
       ++ optionals smbdSupport [ samba ];
  
positive.code:     ++ optional stdenv.isLinux "--enable-linux-aio"
      ++ optional gtkSupport "--enable-gtk"
      ++ optional xenSupport "--enable-xen"
      ++ optional openGLSupport "--enable-opengl"
      ++ optional virglSupport "--enable-virglrenderer"
      ++ optional smbdSupport "--smbd=${samba}/bin/smbd";
  
negative.code: , spiceSupport ? !stdenv.isDarwin, spice, spice-protocol
  , usbredirSupport ? spiceSupport, usbredir
  , xenSupport ? false, xen
  , cephSupport ? false, ceph
  , openGLSupport ? sdlSupport, mesa_noglu, epoxy, libdrm
  , virglSupport ? openGLSupport, virglrenderer
  , smbdSupport ? false, samba
  