with rsc: argsize rounding to 8 smashes stack data on 32bit machines.
with rsc: argsize rounding to 8 smashes stack data on 32bit machines.

R=rsc
http://go/go-review/1024011
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go