Related tdf#93404: Fix deadlock when joining WakeUpThread

...after 54f10a96 "tdf#93404: Forgot to launch
WakeUpThread," when the WakeUpThread blocks on locking
StatusIndicatorFactory::m_mutex in StatusIndicatorFactory::update() while the
joining thread blocks on StatusIndicatorFactory::impl_stopWakeUpThread() ->
WakeUpThread::stop() -> Thread::join().

Change-Id: I3480014b1f522901064ea9b71ffa2ebf5d74fef5

framework/source/helper/statusindicatorfactory.cxx

@@ -550,10 +550,14 @@ void StatusIndicatorFactory::impl_startWakeUpThread()
 
 void StatusIndicatorFactory::impl_stopWakeUpThread()
 {
+    rtl::Reference<WakeUpThread> wakeUp;
+    {
         osl::MutexGuard g(m_mutex);
-    if (m_pWakeUp.is())
+        wakeUp = m_pWakeUp;
+    }
+    if (wakeUp.is())
     {
-        m_pWakeUp->stop();
+        wakeUp->stop();
     }
 }