[bug#65600] [PATCH] Allow parameters AM_PROG_LEX

[Karl Berry]

Hi Bogdan,

    In reference to:
    https://lists.gnu.org/archive/html/automake/2023-07/msg00007.html.

Thanks much!

    Since it's Autoconf 2.70 that started using the parameter, I've
    bumped the required value. 

I don't think we should require the brand-new ac 2.70 just for this
minor feature.  And I think it should be feasible not to: if the
autoconf version is >= 2.70, your new code runs; if <2.70, just ignore
any given argument.  That way people can use the new automake macro with
an older autoconf.

I'm no expert on checking autoconf versions, but from glancing through
the autoconf manual, it looks like m4_version_prereq might be the
simplest to use in this case. It was officially added in ac 2.66, which
should be old enough. It's described at the end of
https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.71/autoconf.html#Number-processing-Macros

Wdyt? Can you tweak your patch along these lines?

Thanks again,
Karl