selinux: Set socket NetLabel based on connection endpoint

Previous work enabled the use of address based NetLabel selectors, which while
highly useful, brought the potential for additional per-packet overhead when
used.  This patch attempts to solve that by applying NetLabel socket labels
when sockets are connect()'d.  This should alleviate the per-packet NetLabel
labeling for all connected sockets (yes, it even works for connected DGRAM
sockets).

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

security/selinux/include/objsec.h

@@ -118,6 +118,7 @@ struct sk_security_struct {
 		NLBL_REQUIRE,
 		NLBL_LABELED,
 		NLBL_REQSKB,
+		NLBL_CONNLABELED,
 	} nlbl_state;
 #endif
 };