[InterNetNews/inn] b43bc5: Use pod2text --guesswork when the option is available

[Julien ÉLIE]

  Branch: refs/heads/main
  Home:   https://github.com/InterNetNews/inn
  Commit: b43bc5d2d2e59f551b26822f36fd1ae3687e46d4
      https://github.com/InterNetNews/inn/commit/b43bc5d2d2e59f551b26822f36fd1ae3687e46d4
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2022-12-26 (Mon, 26 Dec 2022)

  Changed paths:
    M Makefile.global.in
    M configure.ac

  Log Message:
  -----------
  Use pod2text --guesswork when the option is available

New in podlators 5.01 recently published, this option permits disabling
heuristics which prevent some patterns from being converted as expected.

Improve the Autoconf check so that it does not rely on the exit status of
the --help command.