build failure on most platforms

[Bruno Haible]

On most of my test platforms (Debian 9.1, Debian 11.1, CentOS 8-stream,
openSUSE Leap 15.2, Manjaro 17, Alpine Linux, GNU/Hurd, FreeBSD 11,
NetBSD 9, OpenBSD 6.5, Solaris 11 OmniOS, Solaris 11 OpenIndiana,
AIX 7.2, Cygwin, mingw) the build fails already during the configure phase:

checking for gperf... no
configure: error: Could not find gperf

Per GNU Coding Standards
<https://www.gnu.org/prep/standards/html_node/Utilities-in-Makefiles.html>
a package should not require a program such as 'gperf' in order to build.
Instead, all gperf-generated files should be included in the tarball.

You already have liba2ps/confg.c in the tarball. So all you need is
to not use your AC_PROG_GPERF macro. Versions < 2.7 of gperf are no longer
in use for a long time, see https://repology.org/project/gperf/versions .

You can just ditch the m4/gperf-check.m4 file and, in the liba2ps/Makefile.am,
write

  GPERF = gperf

That's what the Gnulib module 'gperf' does. Without problems.

Bruno