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/mes-0.22/lib/tests/scaffold/35-compare-char.c

@@ -0,0 +1,103 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes 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.
+ *
+ * GNU Mes 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 GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <mes/lib-mini.h>
+
+char g_arena[10];
+char *g_chars = g_arena;
+
+int
+main ()
+{
+  int i = 0;
+  char c = 'C';
+  char *p = "mes";
+  char *x = g_arena;
+  char *y = g_chars;
+
+  oputs ("\n");
+  oputs ("t: p[0] != 'm'\n");
+  if (p[0] != 'm')
+    return p[0];
+
+  oputs ("t: p[i] != 't'\n");
+  if (p[i] != 'm')
+    return p[i];
+
+  oputs ("t: *g_chars != 'A'\n");
+  g_arena[0] = 'A';
+  if (*g_chars != 'A')
+    return 1;
+
+  oputs ("t: *x != 'A'\n");
+  if (*x != 'A')
+    return 1;
+
+  oputs ("t: *y != 'A'\n");
+  if (*y != 'A')
+    return 1;
+
+  oputs ("t: *x != 'Q'\n");
+  g_chars[0] = 'Q';
+  if (*x != 'Q')
+    return 1;
+
+  oputs ("t: *x++ != 'C'\n");
+  *x++ = c;
+  if (*g_chars != 'C')
+    return 1;
+
+  oputs ("t: *g_chars == 'B'\n");
+  g_arena[0] = 'B';
+  if (*g_chars == 'B')
+    goto ok1;
+  return 1;
+ok1:
+
+  oputs ("t: *x == 'B'\n");
+  x = g_arena;
+  if (*x == 'B')
+    goto ok2;
+  return 1;
+ok2:
+
+  oputs ("t: *y == 'B'\n");
+  y = g_chars;
+  if (*y == 'B')
+    goto ok3;
+  return 1;
+ok3:
+
+  oputs ("t: *x == 'R'\n");
+  g_chars[0] = 'R';
+  if (*x == 'R')
+    goto ok4;
+  return 1;
+ok4:
+
+  oputs ("t: *x++ == 'C'\n");
+  *x++ = c;
+  if (*g_chars == 'C')
+    goto ok5;
+  return 1;
+ok5:
+
+  return 0;
+}