[arch-dev-public] Changes to x86_64 triplet

Hi all, gcc-6 decided to enforce the vendor part of the target triplet to be not "unknown". This means our vendor string is changed from "unknown" to "pc", aligning with the i686 triplet. I have release a new pacman with the triplet changed in pacman.conf: CHOST="x86_64-pc-linux-gnu" This _should_ have very little effect (the vendor string is quite unimportant). Allan