crossguid: add updateScript

pkgs/development/libraries/crossguid/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub, cmake, libuuid }:
+{ lib, stdenv, fetchFromGitHub, cmake, libuuid, unstableGitUpdater }:
 
 stdenv.mkDerivation rec {
   pname = "crossguid";
@@ -14,6 +14,8 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [ cmake ];
   buildInputs = lib.optional stdenv.isLinux libuuid;
 
+  passthru.updateScript = unstableGitUpdater { };
+
   meta = with lib; {
     description = "Lightweight cross platform C++ GUID/UUID library";
     license = licenses.mit;