I400ToARGB use 8.8 fixed point to avoid a shift. gcc generate constants to avoid fpic performance stall
BUG=none
TEST=none
Review URL: http://webrtc-codereview.appspot.com/322013

git-svn-id: http://libyuv.googlecode.com/svn/trunk@106 16f28f9a-4ce2-e073-06de-1de4eb20be90