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/stdlib/alloca.c

@@ -0,0 +1,102 @@
+/* alloca.c -- allocate automatically reclaimed memory
+   (Mostly) portable public-domain implementation -- D A Gwyn
+
+   Taken from GNU binutils 2.10.1.
+   Minor changes
+   Copyright © 2018,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+
+   This implementation of the PWB library alloca function,
+   which is used to allocate space off the run-time stack so
+   that it is automatically reclaimed upon procedure exit,
+   was inspired by discussions with J. Q. Johnson of Cornell.
+
+   There are some preprocessor constants that can
+   be defined when compiling for your specific system, for
+   improved efficiency; however, the defaults should be okay.
+
+   The general concept of this implementation is to keep
+   track of all alloca-allocated blocks, and reclaim any
+   that are found to be deeper in the stack than the current
+   invocation.  This heuristic does not reclaim storage as
+   soon as it becomes invalid, but it will do so eventually.
+
+   As a special case, alloca(0) reclaims storage without
+   allocating any.  It is a good idea to use alloca(0) in
+   your main control loop, etc. to force garbage collection.  */
+
+#include <stdlib.h>
+#include <unistd.h>
+
+#define ALIGN_SIZE 4
+#define ADDRESS_FUNCTION(arg) &(arg)
+#define STACK_DIR -1
+
+union alloca_header
+{
+  char align[ALIGN_SIZE];       /* To force sizeof(union alloca_header).  */
+  struct
+  {
+    union alloca_header *next;  /* For chaining headers.  */
+    char *deep;                 /* For stack depth measure.  */
+  } h;
+};
+
+static union alloca_header *last_alloca_header = NULL;  /* -> last alloca header.  */
+
+/* Return a void * to at least SIZE bytes of storage,
+   which will be automatically reclaimed upon exit from
+   the procedure that called alloca.  Originally, this space
+   was supposed to be taken from the current stack frame of the
+   caller, but that method cannot be made to work for some
+   implementations of C, for example under Gould's UTX/32.  */
+
+void *
+alloca (size_t size)
+{
+  char probe;                   /* Probes stack depth: */
+  char *depth = ADDRESS_FUNCTION (probe);
+
+  /* Reclaim garbage, defined as all alloca'd storage that
+     was allocated from deeper in the stack than currently.  */
+
+  {
+    union alloca_header *hp;    /* Traverses linked list.  */
+
+    for (hp = last_alloca_header; hp != NULL;)
+      if ((STACK_DIR > 0 && hp->h.deep > depth) || (STACK_DIR < 0 && hp->h.deep < depth))
+        {
+          union alloca_header *np = hp->h.next;
+
+          free ((void *) hp);   /* Collect garbage.  */
+
+          hp = np;              /* -> next header.  */
+        }
+      else
+        break;                  /* Rest are not deeper.  */
+
+    last_alloca_header = hp;    /* -> last valid storage.  */
+
+  }
+
+  if (size == 0)
+    return NULL;                /* No allocation required.  */
+
+  /* Allocate combined header + user data storage.  */
+
+  {
+    void *new = malloc (sizeof (union alloca_header) + size);
+    /* Address of header.  */
+
+    if (new == 0)
+      abort ();
+
+    ((union alloca_header *) new)->h.next = last_alloca_header;
+    ((union alloca_header *) new)->h.deep = depth;
+
+    last_alloca_header = (union alloca_header *) new;
+
+    /* User storage begins just after header.  */
+
+    return (void *) ((char *) new + sizeof (union alloca_header));
+  }
+}