Move config files to /usr/lib/systemd
    
    ... (e.g. /etc/systemd/system.conf → /usr/lib/systemd/systemd.conf).
    Both config file locations were already supported, and the files
    installed in /etc/ were "empty" (i.e. they had only comments and section
    headers). The move does not change the configuration, but just makes
    /etc more empty by default. See
    https://github.com/systemd/systemd/commit/6495361c7d for more
    discussion and details.