Updating opus in .gitignore

BUG=none
TEST=git status in a git-svn checkout.

Review URL: https://webrtc-codereview.appspot.com/965011

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3051 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed