Enable native user/group provide generation for the sysusers feature
Currently systemd has it's own conflicting user/group provide generation
but we need the rpm one for the sysuser integration. This must not
proceed before https://src.fedoraproject.org/rpms/systemd/pull-request/109
is merged + built because this involves a file-level conflict.
Note that this does NOT enable the sysuser integration in rpm, merely
the provides generation, but doing so will allow people to begin testing
the actual integration.