Hooked up RtcEventLog. It lives in Voice Engine and pointers are propagated to ACM and Call.

An option was added to voe_cmd_test to make a RtcEventLog dump.

BUG=webrtc:4741

Review URL: https://codereview.webrtc.org/1267683002

Cr-Commit-Position: refs/heads/master@{#9901}

webrtc/voice_engine/voe_codec_impl.h

@@ -58,6 +58,8 @@ class VoECodecImpl : public VoECodec {
 
   int SetOpusDtx(int channel, bool enable_dtx) override;
 
+  RtcEventLog* GetEventLog() override;
+
  protected:
   VoECodecImpl(voe::SharedData* shared);
   ~VoECodecImpl() override;