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/widgets/qmainwindowlayout.cpp b/src/widgets/widgets/qmainwindowlayout.cpp
index e17fa28b83..9008f023fa 100644
--- a/src/widgets/widgets/qmainwindowlayout.cpp
+++ b/src/widgets/widgets/qmainwindowlayout.cpp
@@ -338,6 +338,7 @@ bool QDockWidgetGroupWindow::event(QEvent *e)
     case QEvent::Resize:
         updateCurrentGapRect();
         emit resized();
+        break;
     default:
         break;
     }