Initial s390-tools-2.0.0 import

This commit is based on the s390-tools-1.39.0 version.

Changes on top of s390-tools-1.39.0:

 - Add MIT license to all source files
 - Add LICENSE file
 - Transform REAMDE to README.md (markdown)
 - Add AUTHORS.md file
 - Add CONTRIBUTING.md file
 - Move changelog from README to CHANGELOG.md file

Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>

dump2tar/include/dref.h

@@ -0,0 +1,29 @@
+/*
+ * dump2tar - tool to dump files and command output into a tar archive
+ *
+ * Reference counting for directory handles
+ *
+ * Copyright IBM Corp. 2016, 2017
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#ifndef DREF_H
+#define DREF_H
+
+#include <dirent.h>
+#include <stdbool.h>
+
+/* Multiple jobs may refer to an open DIR * - need reference counting */
+struct dref {
+	DIR *dd;
+	int dirfd;
+	unsigned int count;
+};
+
+struct dref *dref_create(const char *dirname);
+struct dref *dref_get(struct dref *dref);
+void dref_put(struct dref *dref);
+
+#endif /* DREF_H */