Memcheck suppression. Re-suppress 3478 suppression after namespace change from talk_base to rtc.

BUG=3478
TBR=kjellander@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/15079004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6819 4adac7df-926f-26a2-2b94-8c16560cd09d