anchor.diff:  , xenSupport ? false, xen
   , openGLSupport ? sdlSupport, mesa_noglu, epoxy, libdrm
   , virglSupport ? openGLSupport, virglrenderer
  +, smbdSupport ? false, samba
   , hostCpuOnly ? false
   , nixosTestRunner ? false
   }:
  
positive.code:     ++ optional gtkSupport "--enable-gtk"
      ++ optional xenSupport "--enable-xen"
      ++ optional openGLSupport "--enable-opengl"
      ++ optional virglSupport "--enable-virglrenderer";
  
    doCheck = false; # tries to access /dev
  
  
negative.code:     ++ optionals stdenv.isLinux [ alsaLib libaio libcap_ng libcap attr ]
      ++ optionals xenSupport [ xen ]
      ++ optionals openGLSupport [ mesa_noglu epoxy libdrm ]
      ++ optionals virglSupport [ virglrenderer ]
      ++ optionals smbdSupport [ samba ];
  
    enableParallelBuilding = true;
  
  