selinux: fix memory leak in netlabel code

Fix a memory leak in security_netlbl_sid_to_secattr() as reported here:
 * https://bugzilla.redhat.com/show_bug.cgi?id=352281

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
2 files changed