Morgan Adamiec authored Jan 31, 2019 and Allan McRae committed Jan 31, 2019

Variables such as 'pkgdesc_x86_64' are invalid, instead of ignoring them
raise an error.

This also disallows using 'any' as an architecture specific variable

Signed-off-by: morganamilo <morganamilo@gmail.com>
Signed-off-by: Allan McRae <allan@archlinux.org>