audio_processing/aec: Ported NEON optimizations of SubbandCoherence() and its sub-functions to SSE2

These optimizations were originally committed in r6860, but reverted in r6861, since it broke a bitexactness test (ApmTest.Process) in modules_unittests. That test has now been updated in r7149, hence this CL now pass the test.

BUG=3767
TESTED=manually on linux and trybots
TBR=aluebs@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/25539004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7189 4adac7df-926f-26a2-2b94-8c16560cd09d