Update config.guess and config.sub to the latest version.

In order to make ports like cloudabi-binutils work (PR 200968), we need
to bump up these scripts to the latest upstream version. An exp-run
seems to indicate that this causes no regressions.

PR: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=200967
Differential Revision: D2867
Approved by: antoine