Guix QA: build status "unknown"

[Andy Tai]

I don't know if it is just me, but Guix QA recently seems to always
show build status unknown when what really happens was the build
succeeds on both x86-64 and aarch64 but on other platforms it was in
"scheduled" state but the scheduled build never actually got run.   In
any case thanks to the reviewers/committers some of my patches got
reviewed and committed in this state.

It is just the build status is misleading.   If just x86-64 and
aarch64 builds are used to determine if a patch builds successfully
then the badge should reflect such.