Clang-format ns_core

BUG=webrtc:3811
R=bjornv@webrtc.org, kwiberg@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/29539004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7257 4adac7df-926f-26a2-2b94-8c16560cd09d