Fix -Wimplicit-fallthrough for clang

Clang's `-Wimplicit-fallthrough` warnings are a little stricter than
gcc's interpretation:

switch (i) {
case 0:
    foo();
case 4:
    break;
}

While gcc accepts the implicit fallthrough, if the following statement
is a trivial `break`, clang will warn about it.

Pick-to: 6.7
Change-Id: I38e0817f1bc034fbb552aeac21de1516edcbcbb0
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/widgets/graphicsview/qgraphicsscene.cpp b/src/widgets/graphicsview/qgraphicsscene.cpp
index ad63ff18a0..c022af6fc0 100644
--- a/src/widgets/graphicsview/qgraphicsscene.cpp
+++ b/src/widgets/graphicsview/qgraphicsscene.cpp
@@ -3253,6 +3253,7 @@ bool QGraphicsScene::event(QEvent *event)
         // ### this should only be cleared if we received a new mouse move event,
         // which relies on us fixing the replay mechanism in QGraphicsView.
         d->cachedItemsUnderMouse.clear();
+        break;
     default:
         break;
     }