Add line for HAVE_DYNAMIC_LOADING (result of editing acconfig.h).

This is part of a set of patches by Greg Stein.
diff --git a/config.h.in b/config.h.in
index 8eec1fb..dc38a64 100644
--- a/config.h.in
+++ b/config.h.in
@@ -197,6 +197,9 @@
 */
 #undef HAVE_LARGEFILE_SUPPORT
 
+/* Defined when any dynamic module loading is enabled */
+#undef HAVE_DYNAMIC_LOADING
+
 /* The number of bytes in a int.  */
 #undef SIZEOF_INT