build: build correct cmd/dist matching GOHOSTARCH         Fix for issue 3210 comment #1.
build: build correct cmd/dist matching GOHOSTARCH
        Fix for issue 3210 comment #1.

R=adg, rsc
CC=golang-dev
http://codereview.appspot.com/5794057
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go