network internals: do not try to cache a deleted entry

We were keeping a dangling pointer to a non-existent QIODevice around
which would lead to a crash.

This is not reproducible in Qt5 anymore.

Task-number: QTBUG-17400
Change-Id: I19af701a42e48c05d04dec18eca9f1bfc7e1f4bb
Reviewed-by: Richard J. Moore <rich@kde.org>
Mac: Fix mixing unified and non-unified toolbars

Test if the target toolbar is actually a unified
toolbar before calling the special MapFromParent
function.

This change is not needed in Qt 5. 

Task-number: QTBUG-36100
Change-Id: I37fce89c79f5fce057e0b31d4c4f2e72269cdb06
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>