Rolling new version of opus.gyp

This roll includes changes that enables FIXED_POINT and -O3 for Opus when building for ARM, for higher speed.

BUG=
R=mflodman@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/12749004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6465 4adac7df-926f-26a2-2b94-8c16560cd09d