bug#64236: patch: Ensure that makeinfo ≥ 6.8 checks the @menu structure

[Jim Meyering]

On Thu, Jun 22, 2023 at 4:56 PM Bruno Haible <bruno@clisp.org> wrote:
> Makeinfo versions < 6.7 detected mistakes in the @menu structure of TeXinfo
> input. Makeinfo versions ≥ 6.8 don't do this any more by default. They need
> an extra option, for this validation to happen. See
> <https://lists.gnu.org/archive/html/bug-texinfo/2023-06/msg00015.html>.
>
> Since doc/gzip.texi has a hand-written @menu, it should use this extra
> option.
>
> Here's a patch to that effect.
>
> There are two possibilities for adding the extra option:
>   - in the MAKEINFO variable, where it has an effect on both "makeinfo"
>     and "makeinfo --html",
>   - in the AM_MAKEINFOFLAGS variable, where it has an effect on "makeinfo"
>     only.
> Since some maintainers may check their documentation edits only by 
> regenerating
> the HTML-formatted documentation, the first choice is preferrable.
>
> Tested by running
>   touch doc/gzip.texi ; (cd doc && make gzip.info V=1)
> and
>   make sc_makefile_at_at_check

Thanks again. Pushed.