Correctly set SSRCs for extra send RTP modules.

Fixes a regression introduced in r4096.

BUG=1845
R=mflodman@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/1585004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4134 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed