Add fatal_signal_pending

Like signal_pending, but it's only true for signals which are fatal to
this process

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
diff --git a/kernel/signal.c b/kernel/signal.c
index fd4797f..657aa16 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -994,6 +994,11 @@
 	}
 }
 
+int fastcall __fatal_signal_pending(struct task_struct *tsk)
+{
+	return sigismember(&tsk->pending.signal, SIGKILL);
+}
+
 /*
  * Must be called under rcu_read_lock() or with tasklist_lock read-held.
  */