misc/cgo/test: skip test8694 on ARM.

LGTM=dave, bradfitz, rsc
R=golang-codereviews, dave, bradfitz, rsc
CC=golang-codereviews
https://codereview.appspot.com/185130043

Committer: Russ Cox <rsc@golang.org>
tag go1.4

LGTM=bradfitz, minux
R=golang-codereviews, bradfitz, chaishushan, minux
CC=golang-codereviews
https://codereview.appspot.com/191770043