Added support for sending and receiving RTCP XR packets:

- Receiver reference time report block
- DLRR report block (RFC3611).

BUG=1613
R=mflodman@webrtc.org, stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2196010

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4898 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/rtp_rtcp/source/rtcp_receiver_help.cc

@@ -34,6 +34,8 @@ RTCPPacketInformation::RTCPPacketInformation()
       ntp_secs(0),
       ntp_frac(0),
       rtp_timestamp(0),
+      xr_originator_ssrc(0),
+      xr_dlrr_item(false),
       VoIPMetric(NULL) {
 }