feat(3p/lisp/npg): build using buildLisp

Change-Id: I9f987dc25d77a829cc0716cbe4cb1b91c36de861
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3269
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>

third_party/lisp/npg/default.nix

@@ -0,0 +1,14 @@
+# Copyright (C) 2021 by the TVL Authors
+# SPDX-License-Identifier: LGPL-2.1-or-later
+{ depot, pkgs, ... }:
+
+depot.nix.buildLisp.library {
+  name = "npg";
+
+  srcs = [
+    ./src/package.lisp
+    ./src/common.lisp
+    ./src/define.lisp
+    ./src/parser.lisp
+  ];
+}