VoE: move mock directory 1 level up

Changes:
1. Moved directory voice_engine/include/mock to voice_engine/mock (current recommendation).
2. Updated includes where necessary.

Caution:
We need confirmation that these mocks are indeed used only locally.

R=kwiberg@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/48089004

Cr-Commit-Position: refs/heads/master@{#9005}

webrtc/tools/agc/agc_manager_unittest.cc

@@ -16,8 +16,8 @@
 #include "webrtc/modules/audio_processing/agc/mock_agc.h"
 #include "webrtc/modules/audio_processing/include/mock_audio_processing.h"
 #include "webrtc/system_wrappers/interface/trace.h"
-#include "webrtc/voice_engine/include/mock/fake_voe_external_media.h"
-#include "webrtc/voice_engine/include/mock/mock_voe_volume_control.h"
+#include "webrtc/voice_engine/mock/fake_voe_external_media.h"
+#include "webrtc/voice_engine/mock/mock_voe_volume_control.h"
 #include "webrtc/test/testsupport/trace_to_stderr.h"
 
 using ::testing::_;

webrtc/tools/agc/agc_test.cc

@@ -23,8 +23,8 @@
 #include "webrtc/test/testsupport/trace_to_stderr.h"
 #include "webrtc/tools/agc/agc_manager.h"
 #include "webrtc/tools/agc/test_utils.h"
-#include "webrtc/voice_engine/include/mock/fake_voe_external_media.h"
-#include "webrtc/voice_engine/include/mock/mock_voe_volume_control.h"
+#include "webrtc/voice_engine/mock/fake_voe_external_media.h"
+#include "webrtc/voice_engine/mock/mock_voe_volume_control.h"
 
 DEFINE_string(in, "in.pcm", "input filename");
 DEFINE_string(out, "out.pcm", "output filename");