Modify NetEqQualityTest

- Take input sample rate as parameter - provides resampling when needed.
- Add support for wav output.

BUG=2692
R=minyue@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/49699004

Cr-Commit-Position: refs/heads/master@{#9158}
diff --git a/webrtc/modules/audio_coding/neteq/interface/neteq.h b/webrtc/modules/audio_coding/neteq/interface/neteq.h
index 5d1bbfc..587a1a3 100644
--- a/webrtc/modules/audio_coding/neteq/interface/neteq.h
+++ b/webrtc/modules/audio_coding/neteq/interface/neteq.h
@@ -81,7 +81,7 @@
           background_noise_mode(kBgnOff),
           playout_mode(kPlayoutOn) {}
 
-    int sample_rate_hz;  // Initial vale. Will change with input data.
+    int sample_rate_hz;  // Initial value. Will change with input data.
     bool enable_audio_classifier;
     int max_packets_in_buffer;
     int max_delay_ms;