Reimplement qswap in a more correct manner that works much more cleanly and
with larger string sizes.

--- lib/stdlib/qsort.c
+++ lib/stdlib/qsort.c
@@ -1,6 +1,7 @@
 /* -*-comment-start: "//";comment-end:""-*-
  * GNU Mes --- Maxwell Equations of Software
  * Copyright © 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ * Copyright © 2021 Paul Dersey <pdersey@gmail.com>
  *
  * This file is part of GNU Mes.
  *
@@ -24,10 +25,14 @@
 void
 qswap (void *a, void *b, size_t size)
 {
-  char *buf[8];
-  memcpy (buf, a, size);
-  memcpy (a, b, size);
-  memcpy (b, buf, size);
+  char *pa = a;
+  char *pb = b;
+  do
+  {
+    char tmp = *pa;
+    *pa++ = *pb;
+    *pb++ = tmp;
+  } while (--size > 0);
 }
 
 size_t