Add a new method for restoring original CPU affinity of processes
_restore_ps_affinity() and call that in _instance_init() instead of
_instance_unapply_static(). _instance_unapply_static() touches
instance._terminate, which does not yet exist at that point
(_instance_init always gets a fresh instance object).
The reason this was not a problem in the past is that the true branch
of "if len(instance._scheduler_original) > 0:" was never executed,
because instance._scheduler_original was never correctly saved
to storage. The next commit in this patch series fixes that.
Signed-off-by: Ondřej Lysoněk <olysonek@redhat.com>