I take it all back --- bcopy does handle overlapping source and

destination areas correctly.  At least on every system I could
find.  But it is better to use AC_REPLACE_FUNCS than to introduce
new CPP conditionals.
* memmove.c: New file, implementing memmove in terms of bcopy.
* scmconfig.h.in: Regenerated.

libguile/memmove.c

@@ -0,0 +1,24 @@
+/* Wrapper to implement ANSI C's memmove using BSD's bcopy. */
+/* This function is in the public domain.  --Per Bothner. */
+
+#include <sys/types.h>
+
+#ifdef __STDC__
+#define PTR void *
+#define CPTR const void *
+PTR memmove (PTR, CPTR, size_t);
+#else
+#define PTR char *
+#define CPTR char *
+PTR memmove ();
+#endif
+
+PTR
+memmove (s1, s2, n)
+     PTR s1;
+     CPTR s2;
+     size_t n;
+{
+  bcopy (s2, s1, n);
+  return s1;
+}

libguile/scmconfig.h.in

@@ -176,9 +176,6 @@
 /* Define if you have the atexit function.  */
 #undef HAVE_ATEXIT
 
-/* Define if you have the bcopy function.  */
-#undef HAVE_BCOPY
-
 /* Define if you have the bzero function.  */
 #undef HAVE_BZERO