anchor.diff:      curl
       dbus
       expat
  -    faad2
       ffmpeg
       flac
       fluidsynth
  
positive.code: 
    configureFlags = [
      "--help"
      "--${boolEn (faad2 != null)}-aac"
      # TODO: adplug support
      #"--${boolEn }-adplug" true null)
      "--${boolEn (alsa-lib != null)}-alsa"
  
negative.code: , curl
  , dbus
  , expat
  , ffmpeg
  , flac
  , fluidsynth
  