Fix Makefile after r346467 merged incorrect include file.

MFC: r345994
Fix nfsuserd so that it handles the mapped localhost address when jails
are enabled.

The nfsuserd(8) daemon does not function correctly when jails are enabled,
since localhost gets mapped to another IP address and, as such, the upcall
RPC fails.
This patch fixes the problem by doing a getsockname(2) of a socket mapped
to localhost to find out what the correct address is for the comparison
test with the upcall's from IP address.
This patch also adds INET6 support and the required #ifdef's for INET and
INET6. It now uses INET6 by default for the upcalls, if the kernel has
INET6 support and the daemon is also built with INET6 support.

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

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

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)