nfqws: do not realloc hostname in ipcache if it's the same

nfq/desync.c

@@ -810,6 +810,8 @@ static bool ipcache_put_hostname(const struct in_addr *a4, const struct in6_addr
 		DLOG_ERR("ipcache_put_hostname: out of memory\n");
 		return false;
 	}
+	if (!ipc->hostname || strcmp(ipc->hostname,hostname))
+	{
 		free(ipc->hostname);
 		if (!(ipc->hostname = strdup(hostname)))
 		{
@@ -817,6 +819,7 @@ static bool ipcache_put_hostname(const struct in_addr *a4, const struct in6_addr
 			return false;
 		}
 		DLOG("hostname cached: %s\n", hostname);
+	}
 	return true;
 }
 static bool ipcache_get_hostname(const struct in_addr *a4, const struct in6_addr *a6, char *hostname, size_t hostname_buf_len)