There seems to be some confusion from back when the example were
mass-ported to the QOpenGL stuff in Qt 5 times.
Pick-to: 6.4 6.2
Fixes: QTBUG-109119
Change-Id: Ic4bcd010df3fcf82e16385ce241b379f0c351788
Reviewed-by: Christian Strømme <christian.stromme@qt.io>