Rename Qt-specific GetEventType() to start with "Qt" prefix

This avoids conflicts with another method with the same name defined in
generic wxGenericFileDirButton, which must neither override nor hide
this method of wxButton.

src/qt/anybutton.cpp

@@ -45,7 +45,7 @@ void wxQtPushButton::clicked(bool checked)
     wxAnyButton *handler = GetHandler();
     if ( handler )
     {
-        wxCommandEvent event( handler->GetEventType(), handler->GetId() );
+        wxCommandEvent event( handler->QtGetEventType(), handler->GetId() );
         if ( isCheckable() ) // toggle buttons
         {
             event.SetInt(checked);