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>

libutil/util_scandir_example.c

@@ -0,0 +1,69 @@
+/**
+ * util_dir_example - Example program for util_dir
+ *
+ * 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.
+ */
+
+//! [code]
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lib/util_scandir.h"
+
+/*
+ * Print real sysfs cpu directory contents
+ */
+static void show_cpu_dir(const char *sys_cpu_path)
+{
+	char cmd_ls[256];
+
+	sprintf(cmd_ls, "ls -l %s", sys_cpu_path);
+	printf("$ %s\n", cmd_ls);
+	fflush(stdout);
+	if (system(cmd_ls)) {
+		perror("system() failed");
+		exit(EXIT_FAILURE);
+	}
+	printf("\n");
+}
+
+/*
+ * Show all CPUs on Linux system
+ */
+int main(void)
+{
+	struct dirent **de_vec;
+	int count, i;
+	const char *path = "/sys/devices/system/cpu";
+	const char *prefix = "cpu";
+
+	show_cpu_dir(path);
+
+	/*
+	 * Process all files that match regular expression "cpu[0-9]+"
+	 * and sort them alphabetically. Note that the regular expression
+	 * is constructed with a variable argument list.
+	 */
+	count = util_scandir(&de_vec, alphasort, path, "%s[0-9]+", prefix);
+	if (count == -1) {
+		perror("util_dir_scan failed");
+		return EXIT_FAILURE;
+	}
+
+	/* Print all directories */
+	printf("Found cpus:\n\n");
+	for (i = 0; i < count; i++) {
+		if (de_vec[i]->d_type != DT_DIR)
+			continue;
+		printf(" - %s\n", de_vec[i]->d_name);
+	}
+
+	/* Free directory entries */
+	util_scandir_free(de_vec, count);
+
+	return EXIT_SUCCESS;
+}
+//! [code]