* new file for SSE2 code, code selection through function pointers.
* structure change for array of complex numbers.
* 3.8% AEC overall speedup for straight C path.
* 8.8% AEC overall speedup for SSE2 path.
Review URL: http://webrtc-codereview.appspot.com/34002
git-svn-id: http://webrtc.googlecode.com/svn/trunk@36 4adac7df-926f-26a2-2b94-8c16560cd09d
* new file for SSE2 code, code selection through function pointers.
* structure change for array of complex numbers.
* 3.8% AEC overall speedup for straight C path.
* 8.8% AEC overall speedup for SSE2 path.
Review URL: http://webrtc-codereview.appspot.com/33003
git-svn-id: http://webrtc.googlecode.com/svn/trunk@26 4adac7df-926f-26a2-2b94-8c16560cd09d