Make pbos and kjellander only owners of tsan2 suppressions.

R=pbos@webrtc.org
TBR=kjellander@webrtc.org
BUG=N/A

Review URL: https://webrtc-codereview.appspot.com/29709004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7412 4adac7df-926f-26a2-2b94-8c16560cd09d