Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Fix make buildworld -DMODULES_WITH_WORLD
Sort opt_ srcs

Fix the experimental NFS client so that it does not bogusly
set the f_flags field of "struct statfs". This had the interesting
effect of making the NFSv4 mounts "disappear" after r221014,
since NFSMNT_NFSV4 and MNT_IGNORE became the same bit.
Move the files used for a diskless NFS root from sys/nfsclient
to sys/nfs in preparation for them to be used by both NFS
clients. Also, move the declaration of the three global data
structures from sys/nfsclient/nfs_vfsops.c to sys/nfs/nfs_diskless.c
so that they are defined when either client uses them.

Reviewed by: jhb
MFC after: 2 weeks

Move sys/nfsclient/nfs_lock.c into sys/nfs and build it as a separate
module that can be used by both the regular and experimental nfs
clients. This fixes the problem reported by jh@ where /dev/nfslock
would be registered twice when both nfs clients were used.
I also defined the size of the lm_fh field to be the correct value,
as it should be the maximum size of an NFSv3 file handle.

Reviewed by: jh
MFC after: 2 weeks

Add the kernel build glue for the experimental NFS subsystem that
includes support for NFSv4. The subsystem can optionally be linked
into the kernel using the two options:
NFSCL - the client
NFSD - the server
It is also built as three modules:
nfscl - the client
nfsd - the server
nfscommon - functions shared by the client and server

Approved by: kib (mentor)