Allow same src and dst in InputAudioFile::DuplicateInterleaved

This change allows the input and output to the static method
InputAudioFile::DuplicateInterleaved to be the same array. That is,
in-place manipulation is now possible. A unit test is also added.

R=tina.legrand@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/20239004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7008 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/modules.gyp b/webrtc/modules/modules.gyp
index f68ea7c..138c73b 100644
--- a/webrtc/modules/modules.gyp
+++ b/webrtc/modules/modules.gyp
@@ -153,6 +153,7 @@
             'audio_coding/neteq/mock/mock_external_decoder_pcm16b.h',
             'audio_coding/neteq/mock/mock_packet_buffer.h',
             'audio_coding/neteq/mock/mock_payload_splitter.h',
+            'audio_coding/neteq/tools/input_audio_file_unittest.cc',
             'audio_coding/neteq/tools/packet_unittest.cc',
             'audio_processing/aec/system_delay_unittest.cc',
             'audio_processing/aec/echo_cancellation_unittest.cc',