add arm support to mkasmh
add arm support to mkasmh

R=rsc
APPROVED=rsc
DELTA=5  (5 added, 0 deleted, 0 changed)
OCL=30587
CL=30595
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go