Support both BE and LE MIT master key file formats

Prompted by discussion on heimdal-discuss by Michael Wood, Russ Allbery,
and Henry B. Hotz.

lib/hdb/test_mkey.c

@@ -0,0 +1,55 @@
+
+#include "hdb_locl.h"
+#include <getarg.h>
+#include <base64.h>
+
+static char *mkey_file;
+static int help_flag;
+static int version_flag;
+
+struct getargs args[] = {
+    { "mkey-file",	0,      arg_string, &mkey_file },
+    { "help",		'h',	arg_flag,   &help_flag },
+    { "version",	0,	arg_flag,   &version_flag }
+};
+
+static int num_args = sizeof(args) / sizeof(args[0]);
+
+int
+main(int argc, char **argv)
+{
+    krb5_context context;
+    int ret, o = 0;
+
+    setprogname(argv[0]);
+
+    if(getarg(args, num_args, argc, argv, &o))
+	krb5_std_usage(1, args, num_args);
+
+    if(help_flag)
+	krb5_std_usage(0, args, num_args);
+
+    if(version_flag){
+	print_version(NULL);
+	exit(0);
+    }
+
+    ret = krb5_init_context(&context);
+    if (ret)
+	errx(1, "krb5_init_context failed: %d", ret);
+
+    if (mkey_file) {
+        hdb_master_key mkey;
+
+	ret = hdb_read_master_key(context, mkey_file, &mkey);
+	if (ret)
+	    krb5_err(context, 1, ret, "failed to read master key %s", mkey_file);
+      
+	hdb_free_master_key(context, mkey);
+    } else
+      krb5_errx(context, 1, "no command option given");
+
+    krb5_free_context(context);
+
+    return 0;
+}