skip sock perms test on darwin
skip sock perms test on darwin

Summary:
os.getgroups() can cause LDAP enabled macs to completely beachball for
5 minutes (I had SO MUCH FUN tracking this down!) at a time, so
let's just skip it.

fbshipit-source-id: d92f29258620e5be8cdd93e43c9d43696d24cb8b

nodakai/watchman,facebook/watchman,kwlzn/watchman,wez/watchman,nodakai/watchman,wez/watchman,wez/watchman,facebook/watchman,kwlzn/watchman,wez/watchman,nodakai/watchman,nodakai/watchman,wez/watchman,kwlzn/watchman,facebook/watchman,kwlzn/watchman,nodakai/watchman,nodakai/watchman,facebook/watchman,kwlzn/watchman,nodakai/watchman,wez/watchman,nodakai/watchman,nodakai/watchman,kwlzn/watchman,facebook/watchman,wez/watchman,wez/watchman,kwlzn/watchman,facebook/watchman,facebook/watchman,wez/watchman,facebook/watchman,facebook/watchman