x64: save a bit code size
x64: save a bit code size

It would be better use macro always

BUG=
R=verwaest@chromium.org

Review URL: https://chromiumcodereview.appspot.com/100843002

Patch from Weiliang Lin <weiliang.lin@intel.com>.

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@18282 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh