This allows architecture to be multivalued. On x86-64 machines, this
could be something like:
Architecture = x86-64-v3 x86-64
We use the first specified Architecture value in mirrorlist $arch
variable replacement, as this is backwards-compatible and sane.
More info:
https://git.archlinux.org/pacman.git/commit/?id=3179db108a83104d9de6d1d607f55f8118e92160
Signed-off-by: x1b6e6 <ftdabcde@gmail.com>