socreate(), rather than getting it implicitly from the thread
argument.
o Make NFS cache the credential provided at mount-time, and use
the cached credential (nfsmount->nm_cred) when making calls to
socreate() on initially connecting, or reconnecting the socket.
This fixes bugs involving NFS over TCP and ipfw uid/gid rules, as well
as bugs involving NFS and mandatory access control implementations.
Reviewed by: freebsd-arch
9c4d63da6d