... and do a local code cleanup:
- add override
- port from foreach to C++11 ranged for loop
- remove dead code (`gestureEvent` (née event) was already
dereferenced when we check it for null'ness, so it cannot be
nullptr, so the condition is always true).
Pick-to: 5.15
Change-Id: Ica5e34fbe65c95f6573630f188582b90be15c8f7
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
05a38c05f7