Replaced the old ring buffer in AECM with the new one. Also removed the old one from ring_buffer. Changes are bit exact according to audioproc_unittest fixed. TEST=audioproc_unittest Review URL: http://webrtc-codereview.appspot.com/331022 git-svn-id: http://webrtc.googlecode.com/svn/trunk@1327 4adac7df-926f-26a2-2b94-8c16560cd09d