We finally got the OK from all contributors with non-trivial commits to
relicense systemd from GPL2+ to LGPL2.1+.
Some udev bits continue to be GPL2+ for now, but we are looking into
relicensing them too, to allow free copy/paste of all code within
systemd.
The bits that used to be MIT continue to be MIT.
The big benefit of the relicensing is that closed source code may now
link against libsystemd-login.so and friends.
The property StopRetroactively= needs to be per-dependency, not
per-unit, in order to properly express dependencies between .mount units
and its .device and fsck .service units. If the .device unit is
unplugged the mount should go away, but if the fsck process terminates
the .mount should stay.
