Revert 6312 "Re-enable AudioCodingModuleMtTest"

An example of botbreakage is http://chromegw.corp.google.com/i/client.webrtc/builders/Linux%20Memcheck/builds/1807

> Re-enable AudioCodingModuleMtTest
> 
> Increase timeout and decrease test length. Also fixing a bug in the
> test, and make sure the test aborts if fatal failure occurrs.
> 
> BUG=3426
> R=kwiberg@webrtc.org
> 
> Review URL: https://webrtc-codereview.appspot.com/13579005

TBR=henrik.lundin@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/19609004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6314 4adac7df-926f-26a2-2b94-8c16560cd09d