Update wip/qt3dstudio/master to current head of Qt 5.11.

Note: It would be preferred to compile against stable head of Qt 5.11 (e.g. from qt5.git), but this would require changing the Qt 3D Studio branching scheme from the Qt Creator branching scheme. Qt Creator branching scheme better fits the operation mode of Qt 3D Studio team and Qt 3D Studio as a product that uses Qt, rather than is part of Qt. Unfortunately doing this requires fixing QTQAINFRA-1648.