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/gui/painting/qcssutil.cpp b/src/gui/painting/qcssutil.cpp
index 4792883080..caface7d1a 100644
--- a/src/gui/painting/qcssutil.cpp
+++ b/src/gui/painting/qcssutil.cpp
@@ -268,6 +268,7 @@ void qDrawEdge(QPainter *p, qreal x1, qreal y1, qreal x2, qreal y2, qreal dw1, q
         default:
             break;
         }
+        break;
     }
     default:
         break;