Mention VAAI and ODX in ctl(4).

Reviewed by:	mav@
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation
Fix up an assertion in kern_setgroups, it should compare with ngroups_max + 1

Bug introdued in r273685.

Noted by: Tiwei Bie <btw mail.ustc.edu.cn>
Fix printing non-terminated strings in devlist XML.

MFC after:	1 week