firefox-bin: remove libgnome dependency

It is deprecated and has been removed ages ago:

https://bugzilla.mozilla.org/show_bug.cgi?id=694570

It persists in the crash reporter for some reason but it is optional there:

https://github.com/mozilla/gecko-dev/blob/f66f5a235e7d74c29b951316f73001126a056734/toolkit/crashreporter/client/crashreporter_linux.cpp#L366-L370

pkgs/applications/networking/browsers/firefox-bin/default.nix

@@ -28,8 +28,6 @@
 , libXrender
 , libXt
 , libcanberra
-, libgnome
-, libgnomeui
 , libnotify
 , gnome3
 , libGLU, libGL
@@ -123,8 +121,6 @@ stdenv.mkDerivation {
       libXrender
       libXt
       libcanberra
-      libgnome
-      libgnomeui
       libnotify
       libGLU libGL
       nspr

pkgs/top-level/all-packages.nix

@@ -19761,7 +19761,6 @@ in
     channel = "release";
     generated = import ../applications/networking/browsers/firefox-bin/release_sources.nix;
     gconf = pkgs.gnome2.GConf;
-    inherit (pkgs.gnome2) libgnome libgnomeui;
   };
 
   firefox-bin = wrapFirefox firefox-bin-unwrapped {
@@ -19774,7 +19773,6 @@ in
     channel = "beta";
     generated = import ../applications/networking/browsers/firefox-bin/beta_sources.nix;
     gconf = pkgs.gnome2.GConf;
-    inherit (pkgs.gnome2) libgnome libgnomeui;
   };
 
   firefox-beta-bin = res.wrapFirefox firefox-beta-bin-unwrapped {
@@ -19787,7 +19785,6 @@ in
     channel = "devedition";
     generated = import ../applications/networking/browsers/firefox-bin/devedition_sources.nix;
     gconf = pkgs.gnome2.GConf;
-    inherit (pkgs.gnome2) libgnome libgnomeui;
   };
 
   firefox-devedition-bin = res.wrapFirefox firefox-devedition-bin-unwrapped {