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:   '';
  
    configureFlags =
      [ "--audio-drv-list=${audio}"
        "--sysconfdir=/etc"
        "--localstatedir=/var"
      ]
  