coverity 158147 test ping sprintf bounds

Well, just in the test app arg processing, but yes...

Signed-off-by: Andy Green <andy.green@linaro.org>

test-server/test-ping.c

@@ -450,7 +450,8 @@ int main(int argc, char **argv)
 	/* create client websockets using dumb increment protocol */
 
 	address = argv[optind];
-	sprintf(ads_port, "%s:%u", address, port & 65535);
+	snprintf(ads_port, sizeof(ads_port), "%s:%u",
+		 address, port & 65535);
 	lwsl_notice("Connecting to %s...\n", ads_port);
 	memset(&i, 0, sizeof(i));
 	i.context = context;