[Development] Binary incompatible Qt 5 version

[Peter Kuemmel]

Is it obvious that the Qt 5.4.1 version installed by the system on a KDE
machine is binary incompatible to a locally compiled Qt 5.5.0?

That they are binary incompatible is shown by sporadic QtCreator crashes:
https://bugs.kde.org/show_bug.cgi?id=347524
https://bugreports.qt.io/browse/QTCREATORBUG-14745
The crash happens when QBrush objects are passed around by KDE's style plugin breeze.so.

Peter