Sentinel: fix bufsize to support IPv6 address

Closes #1914

src/sentinel.c

@@ -456,7 +456,7 @@ void sentinelIsRunning(void) {
  *  EINVAL: Invalid port number.
  */
 sentinelAddr *createSentinelAddr(char *hostname, int port) {
-    char buf[32];
+    char buf[REDIS_IP_STR_LEN];
     sentinelAddr *sa;
 
     if (port <= 0 || port > 65535) {
@@ -2690,7 +2690,7 @@ void sentinelCommand(redisClient *c) {
         /* SENTINEL MONITOR <name> <ip> <port> <quorum> */
         sentinelRedisInstance *ri;
         long quorum, port;
-        char buf[32];
+        char buf[REDIS_IP_STR_LEN];
 
         if (c->argc != 6) goto numargserr;
         if (getLongFromObjectOrReply(c,c->argv[5],&quorum,"Invalid quorum")