signal: Use SEND_SIG_PRIV not SEND_SIG_FORCED with SIGKILL and SIGSTOP

Now that siginfo is never allocated for SIGKILL and SIGSTOP there is
no difference between SEND_SIG_PRIV and SEND_SIG_FORCED for SIGKILL
and SIGSTOP.  This makes SEND_SIG_FORCED unnecessary and redundant in
the presence of SIGKILL and SIGSTOP.  Therefore change users of
SEND_SIG_FORCED that are sending SIGKILL or SIGSTOP to use
SEND_SIG_PRIV instead.

This removes the last users of SEND_SIG_FORCED.

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 2a2ac53..c8d5339 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -216,7 +216,7 @@
 	idr_for_each_entry_continue(&pid_ns->idr, pid, nr) {
 		task = pid_task(pid, PIDTYPE_PID);
 		if (task && !__fatal_signal_pending(task))
-			send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
+			send_sig_info(SIGKILL, SEND_SIG_PRIV, task);
 	}
 	read_unlock(&tasklist_lock);
 	rcu_read_unlock();