[PATCH cygport v2] autotools.cygclass: correctly detect Autoconf 2.70+

[Adam Dinwoodie]

On Mon, Mar 14, 2022 at 07:05:20PM +0000, Jon Turney wrote:
> On 13/03/2022 20:44, Adam Dinwoodie wrote:
> >   	configure="${confdir}/configure"
> >   	confver=$(grep -m 1 'GNU Autoconf' ${configure} | cut -d ' ' -f 6)
> > +	confver_maj=${confver%%.*}
> > +	confver_min=${confver##*.}
> > +	if [ $confver_maj -ne 2 ]
> > +	then
> > +		error "unexpected autoconf version";
> > +	fi
> >   	# AC_CONFIG_FILES should not be dist'ed, but it sometimes happens anyway
> >   	eval $(grep -h '^ac_config_files=' ${configure})
> 
> When I test this locally, it fails, as (note the full stop at the end of the
> line):
> 
> > $ grep -m1 Autoconf configure
> > # Generated by GNU Autoconf 2.71.

Huh.  Apparently that string has a less consistent format than I'd
assumed; I'd tested that line against the configure script for Git, but
that gets different behaviour:

    $ grep -m1 Autoconf git-2.35.1-2.x86_64/build/configure
    # Generated by GNU Autoconf 2.71 for git 2.35.1.

I'll try to come up with something a bit less fragile...