Re: _AC_CACHE_DUMP simplified

[Eric Blake]

> 
> Can we avoid 'sed' and 'grep' entirely?  How about this instead?
> 
> case `(ac_space=' '; set) 2>&1` in
> *'
> ac_space= '*)

Are we sure ac_space is not first in the environment, or do we
need something like:

case $as_nl`(ac_space=' '; set) 2>&1` in
*${as_nl}ac_space=\ *)

This is still not robust to something in the environment such
as 'ac_spac="${as_nl}ac_space= "', but the probability of
configuring in an environment that polluted is too small to
be worried about (since we already have a tough time
handling newlines in the environment).

-- 
Eric Blake