And replace all calls with virObjectEventStateQueue such that:

    libxlDomainEventQueue(driver, event);

becomes:

    virObjectEventStateQueue(driver->domainEventState, event);

And remove NULL checking from all callers.
Signed-off-by: NAnya Harter <aharter@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>
Signed-off-by: NJán Tomko <jtomko@redhat.com>