Send 'expired' events when a key expires by lookup.

src/db.c

@@ -543,6 +543,8 @@ int expireIfNeeded(redisDb *db, robj *key) {
     /* Delete the key */
     server.stat_expiredkeys++;
     propagateExpire(db,key);
+    notifyKeyspaceEvent(REDIS_NOTIFY_EXPIRED,
+        "expired",key,db->id);
     return dbDelete(db,key);
 }