MFC: r283635

MFC: r283635
Make the size of the hash tables used by the NFSv4 server tunable.
No appreciable change in performance was observed after increasing
the sizes of these tables and then testing with a single client.
However, there was an email that indicated high CPU overheads for
a heavily loaded NFSv4 and it is hoped that increasing the sizes
of the hash tables via these tunables might help.
The tables remain the same size by default.

git-svn-id: svn://svn.freebsd.org/base/stable/10@284216 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f