Special version of 'bitrv2' when len is 128: * 5.5% AEC overall speedup for the straight C path. * 8.6% AEC overall speedup for the SSE2 path. Review URL: https://webrtc-codereview.appspot.com/480001
Special version of 'bitrv2' when len is 128:
* 5.5% AEC overall speedup for the straight C path.
* 8.6% AEC overall speedup for the SSE2 path.
Review URL: https://webrtc-codereview.appspot.com/480001

git-svn-id: 917f5d3ca488f358c4d40eaec14422cf392ccec9@2004 4adac7df-926f-26a2-2b94-8c16560cd09d

ShiftMediaProject/libilbc,mwgoldsmith/ilbc,TimothyGu/libilbc,mwgoldsmith/ilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,mwgoldsmith/libilbc,mwgoldsmith/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,mwgoldsmith/ilbc,TimothyGu/libilbc,mwgoldsmith/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,mwgoldsmith/libilbc,mwgoldsmith/ilbc