Replace the current license disclaimer in files by
a SPDX-License-Identifier.
Task-number: QTBUG-67283
Change-Id: I708fd1f9f2b73d60f57cc3568646929117825813
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
...and link to Creating Optimized 3D Scenes.
Fixes: QDS-3020
Change-Id: I666afca460e9e0e3afb2b612780f486a094cb45c
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>