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 <[e-mail]>

drivers/tty/tty_audit.c

···
 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;