Fix cluster.c inet_ntop use of sizeof(n->ip).

Using sizeof with an array will only return expected results if the
array is created in the scope of the function where sizeof is used. This
commit changes the inet_ntop calls so that they use the fixed buffer
value as defined in redis.h which is 16.

src/cluster.c

@@ -758,7 +758,7 @@ void nodeIp2String(char *buf, clusterLink *link) {
 
     if (getpeername(link->fd, (struct sockaddr*) &sa, &salen) == -1)
         redisPanic("getpeername() failed.");
-    inet_ntop(sa.sin_family,(void*)&(sa.sin_addr),buf,sizeof(link->node->ip));
+    inet_ntop(sa.sin_family,(void*)&(sa.sin_addr),buf,16);
 }
 
 
@@ -2084,7 +2084,7 @@ void clusterCommand(redisClient *c) {
         /* Finally add the node to the cluster with a random name, this 
          * will get fixed in the first handshake (ping/pong). */
         n = createClusterNode(NULL,REDIS_NODE_HANDSHAKE|REDIS_NODE_MEET);
-        inet_ntop(sa.sin_family,(void*)&(sa.sin_addr),n->ip,sizeof(n->ip));
+        inet_ntop(sa.sin_family,(void*)&(sa.sin_addr),n->ip,16);
         n->port = port;
         clusterAddNode(n);
         addReply(c,shared.ok);