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/linux/x86-mes/elf32-0exit-42.hex2

@@ -0,0 +1,34 @@
+### GNU Mes --- Maxwell Equations of Software
+### Copyright © 2017,2019 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/>.
+
+### Commentary:
+
+# elf32-exit-42.hex2: `exit 42' for i686-linux written in hex2 assembly,
+# for usage with elf32-0header.hex2.  This produces a 112-byte binary
+# (70 hex).  Inspiration was taken from GNU Gcc output of exit-42.S.
+
+### Code:
+
+# @60
+:ELF_text
+b8 01 00 00 00                 # mov    $1, %eax
+bb 2a 00 00 00                 # mov    $42, %ebx
+cd 80                          # int    $0x80
+f4                             # hlt
+00 00 00                       # align to @70
+:ELF_end