RE: autoconf 2.50 tests and cache

[Tim Van Holder]

> Err, you're gonna laugh Pavel, but I don't know how to do this...
> 
> If there is a config.site, then it's loaded *after* the option
> processing (because it depends on $prefix).  Therefore setting
> --cache-file is not an option.
> 
> The only means I can see would be to set CONFIG_SITE for the test
> suite to something which contains nothing, say /dev/null.
> 
Yes, but some platforms (like DJGPP) are not yet 100% supported
directly - we need config.site to make path seraching work.
So disabling config.site would break many tests.
Explicitly setting CONFIG_SITE to the empty string should ensure
the same config.site is loaded during the entire testsuite, so
that should be enough.