anchor.diff:  , libxml2
   , lua
   , libmpeg2
  +, mesa_noglu
   , perl
   , pulseaudio_lib
   , qt4
  
positive.code:     "--enable-dvdnav"
      "--enable-samplerate"
    ] ++ optional onlyLibVLC  "--disable-vlc";
  
    preConfigure = ''
      sed -e "s@/bin/echo@echo@g" -i configure
    '';
  
    preBuild = ''
      substituteInPlace \
  
negative.code:     libxml2
      lua
      libmpeg2
      mesa_noglu
      perl
      pulseaudio_lib
      qt4
  