Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Remove code separator lines which do not conform to style(9).

Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

Reflect license change of NetBSD code.

Obtained from: NetBSD
MFC after: 3 days

Staticify most of fifo/vn operations, they should not
be directly exposed outside.

Approved by: re (tmpfs blanket)

- Sync with NetBSD's RCSID (HEAD preferred).
- Correct a typo.

Approved by: re (tmpfs blanket)

MFp4: Add tmpfs, an efficient memory file system.

Please note that, this is currently considered as an
experimental feature so there could be some rough
edges. Consult http://wiki.freebsd.org/TMPFS for
more information.

For now, connect tmpfs to build on i386 and amd64
architectures only. Please let us know if you have
success with other platforms.

This work was developed by Julio M. Merino Vidal
for NetBSD as a SoC project; Rohit Jalan ported it
from NetBSD to FreeBSD. Howard Su and Glen Leeder
are worked on it to continue this effort.

Obtained from: NetBSD via p4
Submitted by: Howard Su (with some minor changes)
Approved by: re (kensmith)