ACM2 integration with NetEq 4.

nack{.cc, .h, _unittest.cc} are basically copies from main/source/ folder, with cpplint warning cleaned up.

BUG=
R=andrew@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2190009

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@4736 4adac7df-926f-26a2-2b94-8c16560cd09d
60 files changed