MINOR: task/notification: Is notifications registered ?

This function returns true is some notifications are registered.

This function is usefull for the following patch

   BUG/MEDIUM: lua/socket: Sheduling error on write: may dead-lock

It should be backported in 1.6, 1.7 and 1.8
diff --git a/include/proto/task.h b/include/proto/task.h
index ef296f6..760b368 100644
--- a/include/proto/task.h
+++ b/include/proto/task.h
@@ -462,6 +462,13 @@
 	}
 }
 
+/* This function returns true is some notification are pending
+ */
+static inline int notification_registered(struct list *wake)
+{
+	return !LIST_ISEMPTY(wake);
+}
+
 /*
  * This does 3 things :
  *   - wake up all expired tasks