libgnome-keyring: separate $dev output

pkgs/desktops/gnome-3/3.22/core/libgnome-keyring/default.nix

···
     sha256 = "c4c178fbb05f72acc484d22ddb0568f7532c409b0a13e06513ff54b91e947783";
   };
 
+  outputs = [ "out" "dev" ];
+
   propagatedBuildInputs = [ glib gobjectIntrospection dbus_libs libgcrypt ];
   nativeBuildInputs = [ pkgconfig intltool ];