* Regular expression support

  regexp/jimregexp.[ch]:

  Originally:

    Copyright (c) 1986 by University of Toronto.
    Written by Henry Spencer.  Not derived from licensed software.

  Subsequently modified by:

    1986 John Gilmore hoptoad!gnu
    1987 James A. Woods ames!jaw
    1993 Christopher Seiwald seiwald@vix.com
    2000, 2002 Christopher Seiwald <seiwald@perforce.com>
    2010 Steve Bennett <steveb@workware.net.au>
    2020 NIIBE Yutaka <gniibe@fsij.org>

  Permission is granted to anyone to use this software for any
  purpose on any computer system, and to redistribute it freely,
  subject to the following restrictions:

  1. The author is not responsible for the consequences of use of
     this software, no matter how awful, even if they arise
     from defects in it.

  2. The origin of this software must not be misrepresented, either
     by explicit claim or by omission.

  3. Altered versions must be plainly marked as such, and must not
     be misrepresented as being the original software.
