core: fix distcheck

Breakage from e7d0b88e that moved files without updating the Makefile.

changed milestone to %4.0

added Component::Core label

added MRStatus::Reviewable label

mentioned in merge request !69 (merged)

added MRStatus::Acceptable label and removed MRStatus::Reviewable label

I think this should be merged ASAP instead of waiting the usual 24h

Accepted label manually done.

merged

added MRStatus::Accepted label and removed MRStatus::Acceptable label

mentioned in merge request !2840 (merged)