Fix #502: upgrade config.{guess/sub} to most recent

from http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD and
http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD
upgrade config.sub/guess in c-ares as well