Fix comparisons of file ownership on MS-Windows for the Administrator user.
lisp/files.el (file-ownership-preserved-p): Pass `integer' as an
explicit 2nd argument to `file-attributes'. If the file's owner
is the Administrators group on Windows, and the current user is
Administrator, consider that a match.
lisp/server.el (server-ensure-safe-dir): Consider server directory
safe on MS-Windows if its owner is the Administrators group while
the current Emacs user is Administrator. Use `=' to compare
numerical UIDs, since they could be integers or floats.