Make BuildTool version architecture optional
fix(alpm-types): Make BuildTool version architecture optional
The Buildinfov2 buildtool version's architecture turns out to be
actually optional. The architecture isn't set whenever a package is
build with makepkg
directly.
Since this is a usecase that should stay supported, we need to allow this case. Hence the update in code and spec.
Signed-off-by: Arne Beer contact@arne.beer