anchor.diff:    ] ++ optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
         "--cross-prefix=${stdenv.cc.targetPrefix}"
         "--enable-cross-compile"
  -  ] ++ optional stdenv.cc.isClang "--cc=clang";
  +  ] ++ optional stdenv.cc.isClang "--cc=clang");
   
     nativeBuildInputs = [ addOpenGLRunpath perl pkgconfig texinfo yasm ];
   
  
positive.code:   setOutputFlags = false; # doesn't accept all and stores configureFlags in libs!
  
    configurePlatforms = [];
    configureFlags = [
        "--arch=${stdenv.hostPlatform.parsed.cpu.name}"
        "--target_os=${stdenv.hostPlatform.parsed.kernel.name}"
      # License
  
negative.code:       (ifMinVer "0.6" "--enable-pic")
        (enableFeature runtimeCpuDetectBuild "runtime-cpudetect")
        "--enable-hardcoded-tables"
      ] ++
        (if multithreadBuild then (
           if stdenv.isCygwin then
             ["--disable-pthreads" "--enable-w32threads"]
           else # Use POSIX threads by default
             ["--enable-pthreads" "--disable-w32threads"])
         else
           ["--disable-pthreads" "--disable-w32threads"])
      ++ [
        (ifMinVer "0.9" "--disable-os2threads") # We don't support OS/2
        "--enable-network"
        (ifMinVer "2.4" "--enable-pixelutils")
  