zsh variables (was: wish list)

[Ralf Wildenhues]

Hi Eric,

* Eric Blake wrote on Mon, Mar 30, 2009 at 07:09:34PM CEST:
> Double-check that zsh is always in sh mode:
> http://lists.gnu.org/archive/html/autoconf-patches/2008-11/msg00116.html

This one is easy: apparently zsh doesn't unset the $argv array nor the
$ARGC variable when it encounters `emulate sh'.  However, when sh is
(symlinked to) zsh and started as sh, then it does not ever populate
these variables, which may help explain why we haven't seen this before.

One fix could be to just ignore those two variables in AT_CHECK_ENV.

Cheers,
Ralf