newnfs NFS client testing

Hi,

I believe that the new/experimental NFS client in head is now
compatible with the old/regular NFS client.

If you run current and do NFS mounts, testing of the new NFS
client would be appreciated. All you need to do is:
- replace the fstype of "nfs" with "newnfs" in the appropriate
  lines in /etc/fstab

If you are using a diskless NFS root fs, you need to change the
line for "/" in etc/fstab on the root fs on the NFS server plus
add a line like this to boot/loader.conf on the root fs on the server:

vfs.root.mountfrom="newnfs:"

Thanks in advance for any testing, rick
ps: The plan is to switch "newnfs" --> "nfs" soon if problems
    aren't reported.