MFC: r240720

MFC: r240720
Modify the NFSv4 client so that it can handle owner
and owner_group strings that consist entirely of
digits, interpreting them as the uid/gid number.
This change was needed since new (>= 3.3) Linux
servers reply with these strings by default.
This change is mandated by the rfc3530bis draft.
Reported on freebsd-stable@ under the Subject
heading "Problem with Linux >= 3.3 as NFSv4 server"
by Norbert Aschendorff on Aug. 20, 2012.

git-svn-id: svn://svn.freebsd.org/base/stable/8@241306 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f