misc/cgo/test: add missing import
misc/cgo/test: add missing import

Fixes windows build.

R=golang-dev
CC=golang-dev
https://codereview.appspot.com/9429043

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