Notify jitter buffer about received FEC packets (to avoid sending NACK request for these packets).

Don't copy codec specific header for empty packets in the jitter buffer.

BUG=3135
R=pbos@webrtc.org, stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/37659004

Cr-Commit-Position: refs/heads/master@{#8184}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8184 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/rtp_rtcp/source/rtcp_packet_unittest.cc

@@ -572,8 +572,6 @@ TEST(RtcpPacketTest, BuildWithTooSmallBuffer) {
   size_t len = 0;
   uint8_t packet[kRrLength + kReportBlockLength - 1];
   rr.Build(packet, &len, kRrLength + kReportBlockLength - 1);
-  RtcpPacketParser parser;
-  parser.Parse(packet, len);
   EXPECT_EQ(0U, len);
 }