QWS_DISPLAY sounds like it is for QWS, an early Qt4 embedded backend.

Since you say (three times no less) that you are using Qt5, maybe it doesn't change anything because there is no QWS backend in Qt5?

Also, if you intend to run QtCreator on the target, i.e. develop on that machine, why cross compile?
You need a development setup on that machine anyway, no?

Cheers,
_