wsrep_new_cluster: Add -h and --help options

From: https://github.com/devexp-db/mariadb/blob/f27/mariadb-galera-new-cluster-help.patch

scripts/galera_new_cluster.sh

@@ -5,6 +5,22 @@
 # the Free Software Foundation; either version 2.1 of the License, or
 # (at your option) any later version.
 
+if [ "${1}" == "-h" -o "${1}" == "--help" ]; then
+    cat <<EOF
+
+Usage: ${0}
+
+    The script galera_new_cluster is used to bootstrap new Galera Cluster,
+    when all the nodes are down. Run galera_new_cluster on the first node only.
+    On the remaing nodes simply run 'service @DAEMON_NAME@ start'.
+
+    For more information on Galera Cluster configuration and usage see:
+    https://mariadb.com/kb/en/mariadb/getting-started-with-mariadb-galera-cluster/
+
+EOF
+    exit 0
+fi
+
 VERSION="@VERSION@@MYSQL_SERVER_SUFFIX@"
 COMPILATION_COMMENT="@COMPILATION_COMMENT@"