Qt4: allow either COM model for associations (fixes #14323)

The model does not matter here as affected objects do not outlive the
function call and are not used across threads. Still the references
counter of the apartment must remain balanced.

modules/gui/qt4/components/simple_preferences.cpp

@@ -1256,6 +1256,8 @@ void SPrefsPanel::assoDialog()
     HRESULT hr;
 
     hr = CoInitializeEx( NULL, COINIT_MULTITHREADED );
+    if( hr == RPC_E_CHANGED_MODE )
+        hr = CoInitializeEx( NULL, COINIT_APARTMENTTHREADED );
     if( SUCCEEDED(hr) )
     {
         void *p;