A recent commit pushed to the Qt3D repository breaks building Qt3D against Qt version 5.2 and older with the following error message:

painting\qglpainter.cpp:2348:29: error: 'class QOpenGLFunctions' has no member named 'glReadPixels'

Thankfully, rolling back to an older commit still works. Just supply the following command after pulling the Qt3D repository:

git checkout d3338a9 -b older_version

This should enable you to compile Qt3D for Qt5.2 and earlier.