anchor.diff:  
     NIX_CFLAGS_COMPILE = toString [
       "-I${glib.dev}/include/gio-unix-2.0"
  -    "-I${nss.dev}/include/nss"
  +    "-I${nss_pkg.dev}/include/nss"
     ];
   
     MACH_USE_SYSTEM_PYTHON = "1";
  
positive.code:   # 78 ESR won't build with rustc 1.47
    inherit (if lib.versionAtLeast ffversion "82" then rustPackages else rustPackages_1_45)
      rustc cargo;
  in
  
  buildStdenv.mkDerivation ({
  
negative.code:     # yasm can potentially be removed in future versions
      # https://bugzilla.mozilla.org/show_bug.cgi?id=1501796
      # https://groups.google.com/forum/#!msg/mozilla.dev.platform/o-8levmLU80/SM_zQvfzCQAJ
      nspr nss_pkg
    ]
    ++ lib.optional  alsaSupport alsaLib
    ++ lib.optional  pulseaudioSupport libpulseaudio # only headers are needed
  