Update config.guess and config.sub

[Tom Yu]

Julien ÉLIE <julien at trigofacile.com> writes:

> Could they be updated in the next release?  (And, even better, could the 
> update of these two files be added in the release process so that they 
> are always kept up-to-date?)

I've added this step to our release checklist as a manual step.  I don't
want it to happen automatically in the release script because it's best
to test our automated builds on the updated config.{guess,sub} files
before incorporating them into an official release.

-Tom