If the respective modules aren't available we cannot build the tests
and examples. We drop the qtConfig(opengl) requirement for the opengl
examples as
a, we would need to make the QtGui configuration available for that to
work, and
b, we should not add too much detail to the tests and examples build
configurations. Checking each test and example for every feature it
uses would be too much.
Task-number: QTBUG-57255
Change-Id: Ifb043c81ec9e5c487765297bd65704812cd281fc
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
