runtime: disable crash handler test on netbsd
runtime: disable crash handler test on netbsd

Disable the crash handler test on NetBSD until I can figure out why
it triggers failures in later tests.

R=golang-dev, minux.ma
CC=golang-dev
http://codereview.appspot.com/6460090

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