xdg-user-dirs: deprioritize shipped configs

XDG_CONFIG_DIRS should contain directories ordered by priority
so if we want users to be able to customize the defaults, we
need to move the shipped values to the end.

pkgs/tools/X11/xdg-user-dirs/default.nix

@@ -11,8 +11,9 @@ stdenv.mkDerivation rec {
   buildInputs = [ libxslt docbook_xsl makeWrapper ];
 
   preFixup = ''
+    # fallback values need to be last
     wrapProgram "$out/bin/xdg-user-dirs-update" \
-      --prefix XDG_CONFIG_DIRS : "$out/etc/xdg"
+      --suffix XDG_CONFIG_DIRS : "$out/etc/xdg"
   '';
 
   meta = with stdenv.lib; {