Remove intermediate RTCP CNAME buffers.

Sets CNAME using a pointer to only perform a copy inside the RTCP
sender.

BUG=
R=tommi@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/50169005

Cr-Commit-Position: refs/heads/master@{#9346}
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc b/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
index 1afbe01..a79774d 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_rtcp_impl.cc
@@ -493,7 +493,7 @@
   rtcp_receiver_.SetRTCPStatus(method);
 }
 
-int32_t ModuleRtpRtcpImpl::SetCNAME(const char c_name[RTCP_CNAME_SIZE]) {
+int32_t ModuleRtpRtcpImpl::SetCNAME(const char* c_name) {
   return rtcp_sender_.SetCNAME(c_name);
 }