yggdrasil: fix build on darwin

pkgs/tools/networking/yggdrasil/default.nix

@@ -1,4 +1,4 @@
-{ lib, buildGoModule, fetchFromGitHub }:
+{ stdenv, buildGoModule, fetchFromGitHub, Foundation }:
 
 buildGoModule rec {
   pname = "yggdrasil";
@@ -13,6 +13,8 @@ buildGoModule rec {
 
   modSha256 = "057yl3i29kwpd129aa2rb67s5rmz898fi2a7lxv3nfjp7018s9qw";
 
+  buildInputs = stdenv.lib.optionals stdenv.isDarwin [ Foundation ];
+
   # Change the default location of the management socket on Linux
   # systems so that the yggdrasil system service unit does not have to
   # be granted write permission to /run.
@@ -27,7 +29,7 @@ buildGoModule rec {
       -s -w
   '';
 
-  meta = with lib; {
+  meta = with stdenv.lib; {
     description =
       "An experiment in scalable routing as an encrypted IPv6 overlay network";
     homepage = "https://yggdrasil-network.github.io/";