BUG: give the thread some time to finish, so we don't get warnings about a terminated thread.

pqThreadedEventSource.cxx

@@ -95,6 +95,8 @@ pqThreadedEventSource::pqThreadedEventSource(QObject* p)
 
 pqThreadedEventSource::~pqThreadedEventSource()
 {
+  // wait a second for this thread to finish, if it hasn't yet
+  this->Internal->wait(1000);
   delete this->Internal;
 }