CRED: Separate task security context from task_struct

Separate the task security context from task_struct.  At this point, the
security data is temporarily embedded in the task_struct with two pointers
pointing to it.

Note that the Alpha arch is altered as it refers to (E)UID and (E)GID in
entry.S via asm-offsets.

With comment fixes Signed-off-by: Marc Dionne <marc.c.dionne@gmail.com>

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 78f9b31..e210526 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1293,7 +1293,9 @@
 		rcu_read_unlock();
 
 		euid = current_euid();
-		if (euid && euid != tsk->uid && euid != tsk->suid) {
+		if (euid &&
+		    euid != tsk->cred->uid &&
+		    euid != tsk->cred->suid) {
 			put_task_struct(tsk);
 			return -EACCES;
 		}