Bug 1241066 - fix mozRtt always 0 or 1;r=jib

My shortest patch to date.

MozReview-Commit-ID: 8r3ZrGUk40D

--HG--
extra : rebase_source : 38cc51ce85e03c03f46e063bf92f594927d1365f

media/webrtc/trunk/webrtc/modules/rtp_rtcp/source/rtcp_receiver.cc

@@ -568,7 +568,7 @@ void RTCPReceiver::HandleReportBlock(
                      reportBlock->lastReceivedRRNTPfrac);
 
   // time when we received this in MS
-  uint32_t receiveTimeMS = Clock::NtpToMs(reportBlock->lastReceivedRRNTPsecs,
+  uint64_t receiveTimeMS = Clock::NtpToMs(reportBlock->lastReceivedRRNTPsecs,
                                           reportBlock->lastReceivedRRNTPfrac);
 
   // Estimate RTT