Add support for the STATX_ATTR_ flags in statx.  (Compression,
encryption, and the nodump flag are not supported by gfs2.)

Partially fixes xfstest generic/424.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: NAndrew Price <anprice@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>