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/mes/ntoab.c

@@ -0,0 +1,59 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2016,2017,2018,2019 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 <assert.h>
+#include <mes/lib.h>
+
+char *
+ntoab (long x, int base, int signed_p)
+{
+  static char itoa_buf[20];
+  char *p = itoa_buf + 11;
+  *p-- = 0;
+  assert(base > 0);
+
+  int sign_p = 0;
+  unsigned long u;
+  if (signed_p && x < 0)
+    {
+      sign_p = 1;
+      u = -x;
+    }
+  else
+    u = x;
+
+  do
+    {
+      unsigned long i;
+#if __MESC__ && __arm__
+      u = __mesabi_uldiv (u, (unsigned long) base, &i);
+#else
+      i = u % base;
+      u = u / base;
+#endif
+      *p-- = i > 9 ? 'a' + i - 10 : '0' + i;
+    }
+  while (u);
+
+  if (sign_p && *(p + 1) != '0')
+    *p-- = '-';
+
+  return p + 1;
+}