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/ipc/mqueue.c b/ipc/mqueue.c
index abda599..e1885b4 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -126,7 +126,7 @@
 		if (S_ISREG(mode)) {
 			struct mqueue_inode_info *info;
 			struct task_struct *p = current;
-			struct user_struct *u = p->user;
+			struct user_struct *u = p->cred->user;
 			unsigned long mq_bytes, mq_msg_tblsz;
 
 			inode->i_fop = &mqueue_file_operations;