Do not use QMetaType::registerType.

The function is transitional from Qt4 to Qt5. It should not be called.

The patch is a semi cherry-pick of:
 14e247e4b94df17ed62750b4468c2ac25aabe30f
 a49154a75005403185e3813d441fb3e1931af2a2
 1f74dde59f8ecb8be3a41973ab5d8d435815edd6
from qtdeclarative.

Change-Id: I5f90a58d6fa8d1df69e149da22e17e234173dd68
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>