runtime: fix mkasmh.sh for arm?
runtime: fix mkasmh.sh for arm?

The builder is Debian, so maybe running dash,
the shell that time forgot.

R=golang-dev, r
CC=golang-dev
http://codereview.appspot.com/5600053
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go