New comment by jirib on void-packages repository

https://github.com/void-linux/void-packages/issues/19321#issuecomment-589074416

Comment:
Plus, IMO it would be nice to have this file included too:

```
$ grep -IR _unitdir /usr/lib/rpm
/usr/lib/rpm/macros.d/macros.systemd:%_unitdir /usr/lib/systemd/system
```