Fix setting focus on mouse button press in wxUniv

Call base version of HandleMouse to allow the base theme handle to set
the focus to the widget.

Closes #22074.

src/univ/anybutton.cpp

@@ -210,8 +210,6 @@ bool wxStdAnyButtonInputHandler::HandleMouse(wxInputConsumer *consumer,
             m_winHasMouse = true;
 
             consumer->PerformAction(wxACTION_BUTTON_PRESS);
-
-            return true;
         }
         else if ( event.LeftUp() )
         {

src/univ/listbox.cpp

@@ -1439,8 +1439,6 @@ bool wxStdListboxInputHandler::HandleMouse(wxInputConsumer *consumer,
     if ( !action.IsEmpty() )
     {
         lbox->PerformAction(action, item);
-
-        return true;
     }
 
     return wxStdInputHandler::HandleMouse(consumer, event);