runtime/arm: fix build
runtime/arm: fix build

Import _mulv from Inferno again, change R9 to R2.
Not sure what the other differences were for, but
they weren't working.

TBR=kaib
CC=golang-dev
http://codereview.appspot.com/1079041

wesolows/golang-old,wesolows/golang,firebitsbr/golang-old,wesolows/golang,wesolows/golang-old,firebitsbr/golang-old,firebitsbr/golang-old,wesolows/golang,firebitsbr/golang-old,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang,wesolows/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang,firebitsbr/golang-old,wesolows/golang,wesolows/golang,wesolows/golang-old