Delete file acm_neteq_unittest.cc

The file was essentially empty, and not used.

TBR=kwiberg@webrtc.org
NOTRY=true

Review URL: https://codereview.webrtc.org/1804303003

Cr-Commit-Position: refs/heads/master@{#12013}

webrtc/modules/audio_coding/acm2/acm_neteq_unittest.cc

@@ -1,15 +0,0 @@
-/*
- *  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
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-// This file contains unit tests for ACM's NetEQ wrapper (class ACMNetEQ).
-
-namespace webrtc {
-
-namespace acm2 {}  // namespace