bug#67797: non-free license listed in module/ice-9/psyntax.scm

Hello,

In our syntax-case implementation, module/ice-9/psyntax.scm, the
following license text can be found:

--8<---------------cut here---------------start------------->8---
;;; Portable implementation of syntax-case
;;; Originally extracted from Chez Scheme Version 5.9f
;;; Authors: R. Kent Dybvig, Oscar Waddell, Bob Hieb, Carl Bruggeman

;;; Copyright (c) 1992-1997 Cadence Research Systems
;;; Permission to copy this software, in whole or in part, to use this
;;; software for any lawful purpose, and to redistribute this software
;;; is granted subject to the restriction that all copies made of this
;;; software must include this copyright notice in full.  This software
;;; is provided AS IS, with NO WARRANTY, EITHER EXPRESS OR IMPLIED,
;;; INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY
;;; OR FITNESS FOR ANY PARTICULAR PURPOSE.  IN NO EVENT SHALL THE
;;; AUTHORS BE LIABLE FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES OF ANY
;;; NATURE WHATSOEVER.
--8<---------------cut here---------------end--------------->8---

Due to restricting the use to "lawful purpose", it conflicts with the
(L)GPL, as it places restrictions on running the program.

Perhaps there are alternative, clean implementations out there under a
suitable license we could use?

-- 
Thanks,
Maxim