Split the uninstallation of the job from job_free() into a separate function.
Adjust the callers.
job_free() now only works on unlinked and uninstalled jobs. This enforces clear
thinking about job lifetimes.
job_free() is IMO too helpful when it unlinks the job from the transaction.
The callers should ensure the job is already unlinked before freeing.
The added assertions check if anyone gets it wrong.
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.