Improve brevity of type signature

src/const.mli

@@ -44,8 +44,8 @@ val ask : bool option ref
 val no_color : bool ref
 
 (* Files *)
-val rc_file_old : string Core.Std.Lazy.t
-val rc_file : string Core.Std.Lazy.t ref
+val rc_file_old : string Lazy.t
+val rc_file : string Lazy.t ref
 val tmp_file : string
 (* Conf *)
 val default_launch : int