remove event watch on close (#964)

parallel-rdp/interface.cpp

@@ -446,6 +446,8 @@ void rdp_close() {
     delete wsi_platform;
     wsi_platform = nullptr;
   }
+
+  SDL_RemoveEventWatch(sdl_event_filter, nullptr);
 }
 
 static void calculate_viewport(float *x, float *y, float *width, float *height,