Add mes and mescc-tools-extra

mescc-tools-extra contains two important tools:
- cp
- chmod

mes first builds itself from a mes 0.21 seed as used by guix, and then
builds a mes 0.22 and then mes 0.22 using that created mes 0.22.

It does /not/ use bootstrap.sh as we don't have a proper shell at this
point, it has been manually adapted for kaem.

sysa/mescc-tools-extra/functions/require.c

@@ -0,0 +1,31 @@
+/* Copyright (C) 2016 Jeremiah Orians
+ * Copyright (C) 2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ * This file is part of mescc-tools.
+ *
+ * mescc-tools is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * mescc-tools is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with mescc-tools.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include<stdio.h>
+#include<stdlib.h>
+
+void file_print(char* s, FILE* f);
+
+void require(int bool, char* error)
+{
+	if(!bool)
+	{
+		file_print(error, stderr);
+		exit(EXIT_FAILURE);
+	}
+}