polkit_gnome: cleanup, add platforms

pkgs/tools/security/polkit-gnome/default.nix

···
 { stdenv, fetchurl, polkit, gtk3, pkgconfig, intltool }:
 
-stdenv.mkDerivation {
-  name = "polkit-gnome-0.105";
+let
+  version = "0.105";
+
+in stdenv.mkDerivation rec {
+  name = "polkit-gnome-${version}";
 
   src = fetchurl {
-    url = mirror://gnome/sources/polkit-gnome/0.105/polkit-gnome-0.105.tar.xz;
+    url = "mirror://gnome/sources/polkit-gnome/${version}/${name}.tar.xz";
     sha256 = "0sckmcbxyj6sbrnfc5p5lnw27ccghsid6v6wxq09mgxqcd4lk10p";
   };
 
   buildInputs = [ polkit gtk3 ];
   nativeBuildInputs = [ pkgconfig intltool ];
 
-  configureFlags = "--disable-introspection";
+  configureFlags = [ "--disable-introspection" ];
 
   # Desktop file from Debian
   postInstall = ''
···
     description = "A dbus session bus service that is used to bring up authentication dialogs";
     license = stdenv.lib.licenses.gpl2;
     maintainers = with stdenv.lib.maintainers; [ urkud phreedom ];
+    platforms = stdenv.lib.platforms.linux;
   };
 }