Bump up config.{guess,sub} to latest from gnu.org.

Took these and replaced the old ones:
http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD
http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD

The good thing is that apart form the above, the build works fine on AArch64.

Fixes #3