Packages that have an empty hydraPlatforms won't be tested on Hydra otherwise, even if explicitly requested.
Test the GHC boot packages that are known to work with MicroHs and mark those that don't work as broken.
The package set is built entirely from source using the stdenv and Hugs. This also replaces the recently added microhs package, which was built from pre-generated compiler output. Co-authored-by: sternenseemann <sternenseemann@systemli.org>