Update config.guess and config.sub to recent versions

- config.guess: 2014-03-23
- config.sub: 2014-05-01
Debian: Correctly set and use "docdir"
Debian: Don't adjust path names that are correct by default
New "Debian release" 21.1-0ab2

(cherry picked from commit 48fcb97fa4a2762a873d9d693c7a126588a1811d)