Sequence of AudioIO and NetworkManager shutdowns fixes crash at exit

src/AudacityApp.cpp

@@ -2192,6 +2192,10 @@ int AudacityApp::OnExit()
 
    DeinitFFT();
 
+#ifdef HAS_NETWORKING
+   audacity::network_manager::NetworkManager::GetInstance().Terminate();
+#endif
+
    AudioIO::Deinit();
 
    MenuTable::DestroyRegistry();