anchor.diff:  assert sdl2Support        -> available SDL2;
   assert alsaSupport        -> available alsaLib;
   assert screenSaverSupport -> available libXScrnSaver;
  +assert cmsSupport         -> available lcms2;
   assert vdpauSupport       -> available libvdpau;
   assert dvdreadSupport     -> available libdvdread;
   assert dvdnavSupport      -> available libdvdnav;
  
positive.code: , sdl2Support        ? true,  SDL2          ? null
  , alsaSupport        ? true,  alsaLib       ? null
  , screenSaverSupport ? true,  libXScrnSaver ? null
  , vdpauSupport       ? true,  libvdpau      ? null
  , dvdreadSupport     ? true,  libdvdread    ? null
  , dvdnavSupport      ? true,  libdvdnav     ? null
  
negative.code:     ++ optional pulseSupport       libpulseaudio
      ++ optional rubberbandSupport  rubberband
      ++ optional screenSaverSupport libXScrnSaver
      ++ optional cmsSupport        lcms2
      ++ optional vdpauSupport       libvdpau
      ++ optional speexSupport       speex
      ++ optional bs2bSupport        libbs2b
  