VAD refactor: Mode changed to "int".

As part of style this CL includes changing the input aggressiveness mode from int16_t to int. No other style changes made.
Impact on:
- Audio Processing: Changed return value on MapSetting().
- Function test in audio_conference_mixer already uses int. No action.
- NetEq: Function pointer changes and input parameter changes in SetVADMode() and SetVADModeInternal().
- Audio Coding: Uses enum ACMVADMode which is type independent.
- VAD: Two unit tests.

TESTS=vad_unittests, neteq_unittests, audioproc_unittest
Review URL: https://webrtc-codereview.appspot.com/373001

git-svn-id: http://webrtc.googlecode.com/svn/trunk@1544 4adac7df-926f-26a2-2b94-8c16560cd09d

src/modules/audio_coding/neteq/webrtc_neteq.c

@@ -1,5 +1,5 @@
 /*
- *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+ *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
@@ -1632,7 +1632,7 @@ int WebRtcNetEQ_SetVADInstance(void *NetEQ_inst, void *VAD_inst,
  *						  -1 - Error
  */
 
-int WebRtcNetEQ_SetVADMode(void *inst, WebRtc_Word16 mode)
+int WebRtcNetEQ_SetVADMode(void *inst, int mode)
 {
 
     /* Typecast to internal instance type */