Repos were missing reference to the home: 'System' repo

I suspect the dependency solver copes better that way. Not sure though..

The previous fix only worked in the 'gcc_6' repo itself and not in
dependent repositories such as cuda_10_0_gcc_6.

Apparently something has changed upstream and openSUSE has not yet
tracked this in their prjconf, added here meanwhile

Previously, the logic decided that it didn't need to look at the
sub-projects, as the main package is disabled. However, if it was
previously enabled the --disable didn't touch the branched packages in
the sub-projects and those stayed enabled.

- Had old logic for distribution
- Removed '--all' flag to disentangle functionality
  Use mpcdf_setup_subproject if you want to re-create all enabled
  repositories for all packages

This often avoids making an API call to the server completely, if the
generated XML can be shown to be the same as the existing.

- Add 'Runscripts: mpcdf' for 'hcpsw' group creation
- Pre-install a package containing the microarch directories

No with more than one configured API url on my .oscrc it becomes
apparent that this argument was erroneously omitted in the past in many
places.