BUG=none
TESTED=local ios 64 bit build completes without size warnings on xcode 5.1.1
R=harryjin@google.com

Review URL: https://webrtc-codereview.appspot.com/31699004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1120 16f28f9a-4ce2-e073-06de-1de4eb20be90