do not delete public object from private object which is deleted from pub..
Review Request #119541 - Created July 30, 2014 and discarded
this fixes a crash on exit in most polkit apps (most notably kauth kcm
dbusSignalAdd connects the dbus systembus to q, this connection is auto-
disconnect on qobject destruction (i.e. destruction of the public object).
since however public deletes private and private deletes public by the time
the qobject dtor is executed public might be already gone (deleted by the
private) and subsequently the disconnect will fail because there's nothing
this issue is resolved by not establishing a delete cycle.
public manages private and that's the end of it.
test with clock kcm. after removing the delete cycle the helper does no longer crash on exit