anchor.diff:  
     hasXlibs = xlibs != null;
   
  -  optLibcap = if libOnly then null else shouldUsePkg libcap;
  +  optLibcap = shouldUsePkg libcap;
     hasCaps = optLibcap != null || stdenv.isFreeBSD; # Built-in on FreeBSD
   
     optOss = if libOnly then null else shouldUsePkg oss;
  
positive.code:     else shouldUsePkg bluez5;
    optUdev = if libOnly then null else shouldUsePkg udev;
    optOpenssl = if libOnly then null else shouldUsePkg openssl;
    optFftw = if libOnly then null else shouldUsePkg fftw;
    optSpeex = if libOnly then null else shouldUsePkg speex;
    optSystemd = shouldUsePkg systemd;
    optWebrtc-audio-processing = if libOnly then null else shouldUsePkg webrtc-audio-processing;
    hasWebrtc = if libOnly then null else optWebrtc-audio-processing != null;
  
negative.code: , alsaLib ? null, esound ? null, glib ? null, gtk3 ? null, gconf ? null
  , avahi ? null, libjack2 ? null, libasyncns ? null, lirc ? null, dbus ? null
  , sbc ? null, bluez5 ? null, udev ? null, openssl ? null, fftw ? null
  , speexdsp ? null, systemd ? null, webrtc-audio-processing ? null
  
  # Database selection
  , tdb ? null, gdbm ? null
  