OSX: clicking outside a popup: don't propagate the event elsewhere

If you click outside a popup window, it only closes the popup; any
other widget that was under the cursor at that time should not get
the event.  The bug was about the popup list on a combobox, but this
patch assumes that this rule is universal; can't think of any
exceptions at this time.  (E.g. a tooltip is not a popup)  Clicking
on the application menubar still does not close the popup though.

Task-number: QTBUG-33241
Change-Id: I2444b7cfd40cf75ff7b70e3fecfeceb2fd4623bf
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>

src/plugins/platforms/cocoa/qnsview.mm

@@ -600,6 +600,7 @@ static QTouchDevice *touchDevice = 0;
         QWindowSystemInterface::handleCloseEvent(m_platformWindow->m_activePopupWindow);
         QWindowSystemInterface::flushWindowSystemEvents();
         m_platformWindow->m_activePopupWindow = 0;
+        return;
     }
     if ([self hasMarkedText]) {
         NSInputManager* inputManager = [NSInputManager currentInputManager];