Teach cpio to set uid/gid and timestamp. (Timestamp has year 2100 problem.)

Teach cpio to set uid/gid and timestamp. (Timestamp has year 2100 problem.)

Note that directory timestamps are still sometimes wrong because creating
things in a directory can update the timestamp. Also, cp -r has logic to
ensure we can write to a directory that doesn't have write permission,
cpio does not. This is fixable, but not what existing cpio does.