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/search-path.c

@@ -0,0 +1,66 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 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 <mes/lib.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+char *
+search_path (char const *file_name)
+{
+  static char buf[256];
+  char *path = getenv ("PATH");
+  if (__mes_debug ())
+    {
+      eputs ("\n search-path: ");
+      eputs (file_name);
+      eputs ("\n");
+    }
+  while (*path)
+    {
+      char *end = strchr (path, ':');
+      if (!end)
+        end = strchr (path, '\0');
+      strncpy (buf, path, end - path);
+      buf[end - path] = 0;
+      if (__mes_debug ())
+        {
+          eputs (" dir: ");
+          eputs (buf);
+          eputs ("\n");
+        }
+      if (buf[end - path] != '/')
+        strcat (buf, "/");
+      strcat (buf, file_name);
+      if (!access (buf, X_OK))
+        {
+          if (__mes_debug ())
+            {
+              eputs (" found: ");
+              eputs (buf);
+              eputs ("\n");
+            }
+          return buf;
+        }
+      path = end + 1;
+    }
+  return 0;
+}