lib: tiny cleanup

lib/customisation.nix

···
       auto = builtins.intersectAttrs (lib.functionArgs f) autoArgs;
       origArgs = auto // args;
       pkgs = f origArgs;
-      mkAttrOverridable = name: pkg: makeOverridable (newArgs: (f newArgs).${name}) origArgs;
+      mkAttrOverridable = name: _: makeOverridable (newArgs: (f newArgs).${name}) origArgs;
     in lib.mapAttrs mkAttrOverridable pkgs;