Shoot from hip diff, based on listenerStop() logic but applied to
Filter.destroy(). Sorry I'm unable to build TC5 from SVN or the -src package.
I'm taking the thought here that I know I have active filters on my web-app and
the reason why it affects me is that when I renamed the directory I removed the
JVMs ability to find and load the Filter#destroy() function.
In any case this patch feels like the correct thing to do.