./configure --enable/disable-kdbus can be used to set the default
behavior regarding kdbus.
If no kdbus kernel support is available, dbus-dameon will be used.
With --enable-kdbus, the kernel command line option "kdbus=0" can
be used to disable kdbus.
With --disable-kdbus, the kernel command line option "kdbus=1" is
required to enable kdbus support.
Choose which system users defined in sysusers.d/systemd.conf and files
or directories in tmpfiles.d/systemd.conf, should be provided depending
on comile-time configuration.