[MINOR] Add a default empty configuration

When downloading systemds and running from source, there is no
configuration file named .xml in the conf folder,
this makes the systemds binary look for a configuration file in the
test folders, where the first one is a compression settings file.

This commit remove this flaw, and defaults to a defaults xml file,
that set none of our flags.

conf/SystemDS-config-defaults.xml

@@ -0,0 +1,21 @@
+<!--
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+-->
+
+<root>
+</root>