bug fix in 6c/8c/5c mis-aligned function arguments.
bug fix in 6c/8c/5c mis-aligned
function arguments.

R=rsc
CC=golang-dev
http://codereview.appspot.com/206054
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go