Make Akonadi compile without QT_STRICT_ITERATORS
Summary:
Without QT_STRICT_ITERATORS QVector and QList iterators do not satisfy the
STL iterator requirements since they are simply just T*. We can work around
that by introducing a helper to provide the necessary traits for those.
At the same time, turns out QT_STRICT_ITERATORS does not introduce any
overhead (they are inlined so everything gets optimized), confirmed by
comparing the produced assembly in Compiler Explorer.
Test Plan: Compiles
Reviewers: vkrause, dfaure
Reviewed By: dfaure
Subscribers: kde-pim
Tags: KDE PIM
Differential Revision: https://phabricator.kde.org/D20306