anchor.diff:      "--${boolEn (gmp != null)}-gmp"
       "--${boolEn (gnutls != null)}-gnutls"
       "--${boolEn (stdenv.cc.libc != null)}-iconv"
  -    "--${boolEn (jack2_lib != null)}-jack"
  +    (deprfflag "--${boolEn (jack2_lib != null)}-jack" null "3.4")
       "--${boolEn (jni != null)}-jni"
       "--${boolEn (ladspa-sdk != null)}-ladspa"
       "--${boolEn (libass != null)}-libass"
  
positive.code:     /**/"--disable-omx-rpi"
      /**/"--disable-rkmpp"
      "--${boolEn (libva != null)}-vaapi"
      "--disable-vda"  # macOS
      "--${boolEn (libvdpau != null)}-vdpau"
      "--disable-videotoolbox"  # macOS
      # Undocumented
  
negative.code:     "--disable-libiec61883"
      #"--${boolEn (ilbc != null)}-libilbc"
      "--disable-libilbc"
      (fflag "--${boolEn (jack2_lib != null)}-libjack" "3.5")
      "--${boolEn (kvazaar != null)}-libkvazaar"
      "--${boolEn (libmodplug != null)}-libmodplug"
      "--${boolEn (lame != null)}-libmp3lame"
  