libselinux: optimize set*con functions

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

This patch looks good to me. acked.

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.13 (GNU/Linux)
Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/

iEYEARECAAYFAlD+qX4ACgkQrlYvE4MpobO9VQCffAy0N7x2NCiln61Tv6gPLIcp UtMAnjGJa+ex95zTiFB0j73P+yh3IaeJ
=6rZI
-----END PGP SIGNATURE-----