Reconfigure default streams on AddRecvStream.

Makes sure RTX can be used for streams that have received early media
before being properly configured.

BUG=1788
R=mflodman@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/46499004

Cr-Commit-Position: refs/heads/master@{#8634}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8634 4adac7df-926f-26a2-2b94-8c16560cd09d
4 files changed