Make layoutDirection pass with new expose behavior

A QMenu with no actions gets a size of (0, 0) on OS X.
With the new stricter expose event behavior this
is considered invalid geometry and the platform plugin
won't send an expose event, causing the qWaitForWindowExposed
test to fail.

Add a menu entry since the layoutDirection test is
not really interested in testing the special case of
empty menus.

Change-Id: I5221dc3f0472ac13edf821df08bacc3a4eb5cd9d
Reviewed-by: Simo Fält <simo.falt@digia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

tests/auto/widgets/widgets/qmenu/tst_qmenu.cpp

@@ -570,6 +570,7 @@ void tst_QMenu::layoutDirection()
     win.setLayoutDirection(Qt::RightToLeft);
 
     QMenu menu(&win);
+    menu.addAction("foo");
     menu.show();
     QVERIFY(QTest::qWaitForWindowExposed(&menu));
     QCOMPARE(menu.layoutDirection(), Qt::RightToLeft);