Revert "Make VoiceEngine choose ACM2 by default"
Revert "Make VoiceEngine choose ACM2 by default"

The reason for reverting is that Issue 3143 should be resolved
first.

TBR=henrika@webrtc.org
BUG=3143

Review URL: https://webrtc-codereview.appspot.com/12119005

git-svn-id: 917f5d3ca488f358c4d40eaec14422cf392ccec9@5926 4adac7df-926f-26a2-2b94-8c16560cd09d

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