Added SDL_CleanupEvent()

This is used to free any dynamically allocated memory in events.

test/checkkeysthreads.c

@@ -183,6 +183,7 @@ static void loop(void)
             break;
         case SDL_EVENT_TEXT_EDITING:
             PrintText("EDIT", event.text.text);
+            SDL_CleanupEvent(&event);
             break;
         case SDL_EVENT_TEXT_INPUT:
             PrintText("INPUT", event.text.text);