Cocoa: Make QMacNativeWidget event processing work

Don't interrupt the Qt event loop if the Qt event
loop isn't running (meaning processEvents has not/
will not be called). This can happen in the QMacNativeWidget
or plugin case where the native code calls [NSApp run]
and QApplication::exec() is never called.

In Qt 4 this was not necessary since UI event
processing was more direct: QCocoaView would call
QCoreApplication::sendMouseEvent/sendSpontaneousEvent
directly on mouse events.

Task-number: QTBUG-36225
Change-Id: I2894cbbca66a902652c9f8bc916e94ad8ce0e18e
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>

src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm

@@ -870,7 +870,7 @@ void QCocoaEventDispatcherPrivate::processPostedEvents()
         return;
     }
 
-    if (interrupt) {
+    if (processEventsCalled > 0 && interrupt) {
         if (currentExecIsNSAppRun) {
             // The event dispatcher has been interrupted. But since
             // [NSApplication run] is running the event loop, we