experimental client is used when the fstype is "newnfs" or the "nfsv4"
option is specified. It includes the addition of the option:
gssname - to specify a client side initiator host based principal name
which is specific to NFSv4.
It also includes a change to mount.c, so that it knows about
mount_newnfs, but not mount_nfs4.
Reviewed by: dfr
Approved by: kib (mentor)
011981fd9e