tst_Gestures: compile with QT_NO_FOREACH [1/2]

GestureWidget::ignoredGestures QSet:
- elements are inserted in the container in a top-level test function,
  then a CustomEvent is constructed and sendCustomGesture() is called,
  which sends the events, invoking the GestureWidget::event() overload,
  the latter iterates over the container, thus the container isn't
  changed while it's being iterated over, because the code can't recurse
  into the top-level test function and that's where the container is
  modified later on (by inserting or by calling widget.reset() which
  clears the container)
- the loop body doesn't change the container

So use ranged-for and std::as_const.

The same logic applies to the GestureItem::ignoredGestures QSet.

Task-number: QTBUG-115839
Change-Id: Icf95e90a8af5aa7e947035704121557494afc326
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

tests/auto/other/gestures/tst_gestures.cpp

@@ -210,7 +210,7 @@ protected:
             QGestureEvent *e = static_cast<QGestureEvent*>(event);
             ++gestureEventsReceived;
             eventsPtr = &events;
-            foreach(Qt::GestureType type, ignoredGestures)
+            for (Qt::GestureType type : std::as_const(ignoredGestures))
                 e->ignore(e->gesture(type));
         } else if (event->type() == QEvent::GestureOverride) {
             ++gestureOverrideEventsReceived;
@@ -744,7 +744,7 @@ public:
             ++gestureEventsReceived;
             eventsPtr = &events;
             QGestureEvent *e = static_cast<QGestureEvent *>(event);
-            foreach(Qt::GestureType type, ignoredGestures)
+            for (Qt::GestureType type : std::as_const(ignoredGestures))
                 e->ignore(e->gesture(type));
             foreach(QGesture *g, e->gestures()) {
                 switch (g->state()) {