Merge pull request #4497 from soloestoy/optimize-unlink-client

networking: optimize unlinkClient() in freeClient()

src/server.h

@@ -733,6 +733,7 @@ typedef struct client {
     dict *pubsub_channels;  /* channels a client is interested in (SUBSCRIBE) */
     list *pubsub_patterns;  /* patterns a client is interested in (SUBSCRIBE) */
     sds peerid;             /* Cached peer ID. */
+    listNode *client_list_node; /* list node in client list */
 
     /* Response buffer */
     int bufpos;