Remove unused Cleanup() call

It was used to clean up shared memory.  We don't construct that anymore,
so remove the useless call.

Change-Id: I8087cef2afce184f66721a9995a63053fb278ec7
diff --git a/y2019/joystick_reader.cc b/y2019/joystick_reader.cc
index 59906c7..5dc75a7 100644
--- a/y2019/joystick_reader.cc
+++ b/y2019/joystick_reader.cc
@@ -673,5 +673,5 @@
 
   event_loop.Run();
 
-  ::aos::Cleanup();
+  return 0;
 }