Add missing newline to output dmesg properly.
Remove unused macro VT_CONSDEV_DECLARE. Join console device now declared in one
place.

MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
o Remove useless debug string.
o Fix indent.

MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Assert that nullfs vnode has VV_ROOT set whenever lower vnode has.
Assert that dotdot lookup on the root vnode is not performed.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week