* autoconf/acinclude.m4: revamp MPN-matcher.

    * autoconf/acinclude.m4: revamp MPN-matcher.
        * autoconf/aclocal.m4: upgrade to autoconf-2.52 infrastructure,
          sync with CLisp from CVS.
        * autoconf/autoconf: Likewise.
        * autoconf/autoconf.m4f: Likewise (new file).
        * configure.ac: Likewise (new file, replaces configure.in).
        * configure.in: Likewise (deleted, replaced by configure.ac).
        * autoconf/config.{guess,sub}: Update to GNU version 2001-12-13.
        * src/Makefile.in: made VPATH safe for autoconf-2.52.
        * include/cln/config.h.in: Add __s390__.