Cleanup temporary class files for OpenSlDemo

I've seen tryjobs failing when they shouldn't on
the Android trybots and I suspect this might have
something to do with it.

TBR=henrike@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/20339004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7091 4adac7df-926f-26a2-2b94-8c16560cd09d