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

Change the NFSv4 nfsuserd(8) daemon so that it doesn't preload the
uid<->username mapping cache with an entry when another entry
for that uid is already loaded. This fixes a case where the
mapping of "toor" would replace "root" when the daemon was started,
resulting in no mapping for "root" until the cache entry for "toor"
timed out.
The algorithm is inefficient, but since it is only done once when
the daemon is started up, I don't think that's an issue.

MFC after: 2 weeks

Fix typos and spelling mistakes.

Code cleanup for nfs4 utilities:

- Mark internal routines as static;
- Eliminate unused parameters where possible, mark __unused for others;
- Remove unused variables;
- Use %jd for int64_t values in printf();
- Add appropriate %d for printf to match its parameter;
- Rename a variable to resolve conflict with revoke(2);

Reviewed by: rmacklem
Tested with: make universe (bugs are mine)

Add two new utilities and two new daemons to /usr/src/usr.sbin that
are specifically used by the experimental nfsv4 subsystem.
nfscbd - The NFSv4 client callback daemon.
nfsuserd - The NFSv4 daemon that maps between user and group name
and their corresponding uid/gid numbers.
nfsdumpstate - A utility that dumps out the NFSv4 Open/Lock state.
nfsrevoke - Administratively revokes an NFSv4 client, releasing all
NFSv4 Open/Lock state it holds on the server.

Approved by: kib (mentor)