4294 fopen could support 'x'
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Joshua M. Clulow <jmc@joyent.com>
Reviewed by: Jason King <jason.brian.king@gmail.com>
Reviewed by: Marcel Telka <marcel@telka.sk>
Reviewed by: Garrett D'Amore <garrett@damore.org>
Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Approved by: Gordon Ross <gordon.ross@nexenta.com>