apparmor: fix replacement bug that adds new child to old parent

When set atomic replacement is used and the parent is updated before the
child, and the child did not exist in the old parent so there is no
direct replacement then the new child is incorrectly added to the old
parent. This results in the new parent not having the child(ren) that
it should and the old parent when being destroyed asserting the
following error.

AppArmor: policy_destroy: internal error, policy '<profile/name>' still
contains profiles

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>