Bugfix release.
-Fix build on OSX
-Fix build when using optional features AND those optional libraries decided to build against libsystemd (not sure which one, but it doesn't matter).
-Python 3.8 compatibility issues
(Packagers: The .tar.gz file is to make it easier to build from source, as it doesn't require autoconf. It is hand-made so please use the autogenerated from git version instead.)