When comparing mtimes for the -u and -Z options and the target is

When comparing mtimes for the -u and -Z options and the target is
'too old', use pathconfat(_PC_TIMESTAMP_RESOLUTION, AT_SYMLINK_NOFOLLOW)
to get the timestamp resolution to which the _source_ timestamp
should be truncated for a stable comparison.

Problem reported by Walter Alejandro Iglesias (wai(at)roquesor.com)
ok millert@