LabPlot builds and runs with kf5

[Marko Käning]

Hi Alexander,

just for your information, Scarlett’s new multi-platform CI system already allows - apart from
the obligatory Linux - for building on OSX. :-)

Although playground or review projects are usually not in CI I introduced you project, so that
you’ll have better insight into where things fail:

   https://build-sandbox.kde.org/view/FAILED%20OSX%20(KF5)/job/labplot%20frameworks%20kf5-qt5/

This might help you figuring out a solution on your own, without me testing patches for you...

PLUS you don’t need your own OSX setup for all of this.

Greets,
Marko