chore(3p/lisp): import npg source tarball

Used http://wcp.sdf-eu.org/software/npg-20150517T144652.tbz (sha256
42e88f6067128fbdb3a3d578371c9b0ee2a34f1d36daf80be8a520094132d828).
There's no upstream repository nor a release since 2015, so importing
seems to make a lot of sense.

Since we can't subtree making any depot-related changes in a separate CL
-- this is only the source import.

Change-Id: I64c984ca0a84b9e48c6f496577ffccce1d7bdceb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3377
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>

third_party/lisp/npg/README

@@ -0,0 +1,41 @@
+
+		     NPG a Naive Parser Generator
+			   for Common Lisp
+
+	 Copyright (C) 2003-2006, 2010 by Walter C. Pelissero
+
+This library is  free software; you can redistribute  it and/or modify
+it  under  the terms  of  the GNU  Lesser  General  Public License  as
+published by the  Free Software Foundation; either version  2.1 of the
+License,  or (at  your option)  any  later version.   This library  is
+distributed  in the  hope  that it  will  be useful,  but WITHOUT  ANY
+WARRANTY;  without even  the  implied warranty  of MERCHANTABILITY  or
+FITNESS FOR A  PARTICULAR PURPOSE.  See the GNU  Lesser General Public
+License for more details.  You should  have received a copy of the GNU
+Lesser General Public  License along with this library;  if not, write
+to the  Free Software  Foundation, Inc., 59  Temple Place,  Suite 330,
+Boston, MA 02111-1307 USA
+
+
+This library generates on the fly (no external representation of the
+parser is produced) a recursive descent parser based on the grammar
+rules you have fed it with.  The parser object can then be used to
+scan tokenised input.  Although a facility to produce a lexical
+analiser is not provided, to write such a library is fairly easy for
+most languages.  NPG parsers require your lexer to adhere to a certain
+protocol to be able to communicate with them.  Examples are provided
+that explain these requirements.
+
+While quite possibly not producing the fastest parsers in town, it's
+fairly simple and hopefully easy to debug.  It accepts a lispy EBNF
+grammar description of arbitrary complexity with the exception of
+mutually left recursive rules (watch out, they produce undetected
+infinite recursion) and produces a backtracking recursive descent
+parser.  Immediate left recursive rules are properly simplified,
+though.
+
+Multiple concurrent parsers are supported.
+
+To compile, an ASDF file is provided.
+
+See the examples directory for clues on how to use it.