anchor.diff:  
     passthru = { inherit openglSupport; };
   
  +  enableParallelBuilding = true;
  +
     meta = with stdenv.lib; {
       description = "A cross-platform multimedia library";
       homepage    = "http://www.libsdl.org/";
  
positive.code: 
    nativeBuildInputs = [ pkgconfig ];
  
    propagatedBuildInputs = [ ]
      ++ optionals x11Support [ libXext libICE libXrandr ]
      ++ optional stdenv.isLinux libcap
      ++ optionals openglSupport [ libGL libGLU ]
  
negative.code:     ++ optional pulseaudioSupport libpulseaudio
      ++ optional stdenv.isDarwin Cocoa;
  
    buildInputs = [ ]
      ++ optional (!hostPlatform.isMinGW) audiofile
      ++ optionals stdenv.isDarwin [ AudioUnit CoreAudio CoreServices Kernel OpenGL ];
  
  