audit: do not needlessly take a lock in tty_audit_exit

We were doing spin_lock_irq and spin_unlock_irq.  This is STOOPID.

If we were in interupt context we were already screwed and called
panic() in do_exit().  So the irq stuff is useless.  Also, these values
can only be changed by receiving a netlink message from current.  Since
we are in do_exit() clearly we aren't in the syscall sending the netlink
message to change these values.  Thus, just read them and go with it.
Signed-off-by: Eric Paris <eparis@redhat.com>

drivers/tty/tty_audit.c

@@ -111,12 +111,9 @@ static void tty_audit_buf_push(struct tty_audit_buf *buf)
 void tty_audit_exit(void)
 {
 	struct tty_audit_buf *buf;
-	unsigned long flags;
 
-	spin_lock_irqsave(&current->sighand->siglock, flags);
 	buf = current->signal->tty_audit_buf;
 	current->signal->tty_audit_buf = NULL;
-	spin_unlock_irqrestore(&current->sighand->siglock, flags);
 	if (!buf)
 		return;