in rtp_rtcp module:
  fixed build/namespaces lint errors
  fixed readability/namespace lint errors

BUG=webrtc:5277
R=mflodman,stefan@webrtc.org

Review URL: https://codereview.webrtc.org/1506823002

Cr-Commit-Position: refs/heads/master@{#10978}
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_utility.h b/webrtc/modules/rtp_rtcp/source/rtcp_utility.h
index e1f8737..0b03ceb 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_utility.h
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_utility.h
@@ -487,6 +487,6 @@
 
   RtcpCommonHeader _header;
 };
-}  // RTCPUtility
+}  // namespace RTCPUtility
 }  // namespace webrtc
 #endif // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_UTILITY_H_