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/include/errno.h

@@ -0,0 +1,72 @@
+/* -*-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/>.
+ */
+#ifndef __MES_ERRNO_H
+#define __MES_ERRNO_H 1
+
+#if SYSTEM_LIBC
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#undef __MES_ERRNO_H
+#include_next <errno.h>
+#else // ! SYSTEM_LIBC
+
+#ifndef __MES_ERRNO_T
+#define __MES_ERRNO_T 1
+typedef int error_t;
+int errno;
+#endif // !__MES_ERRNO_T
+
+int errno;
+#define ENOENT   2
+#define EINTR    4
+#define EIO      5
+#define ENXIO    6
+#define E2BIG    7
+#define ENOEXEC  8
+#define EBADF    9
+#define	ECHILD  10
+#define EAGAIN  11
+#define ENOMEM  12
+#define EACCES  13
+#define EEXIST  17
+#define EXDEV   18
+#define ENOTDIR 20
+#define EISDIR  21
+#define EINVAL  22
+#define EMFILE  24
+#define ENOSPC  28
+#define ESPIPE  29
+#define EPIPE   32
+#define ERANGE  34
+
+#define ENAMETOOLONG 36
+#define ENOSYS 38
+#define ELOOP  40
+
+#if !__MESC__
+//extern char const *const sys_errlist[];
+extern char *sys_errlist[];
+extern int sys_nerr;
+#endif // !__MESC__
+
+#endif // ! SYSTEM_LIBC
+
+#endif // __MES_ERRNO_H