anchor.diff:  , libwebp
   , mesa
   , mpg123
  +, musepack
   , openal
   #, opencv
   , openh264
  
positive.code:     #(enFlag "mpeg2enc" ( != null) null)
      (enFlag "mpg123" (mpg123 != null) null)
      #(enFlag "mplex" ( != null) null)
      (enFlag "musepack" (libmpcdec != null) null)
      #(enFlag "nas" ( != null) null)
      #(enFlag "neon" ( != null) null)
      #(enFlag "ofa" ( != null) null)
  
negative.code: , libbs2b
  , libmms
  , libmodplug
  , libopus
  , librsvg
  , libsndfile
  