Without the correct prototype for malloc() brought in from
stdlib.h, the compiler assumes the result is an integer not
a pointer. On 64-bit arch this causes pointer truncation.

$OpenBSD: patch-xmlmemory_h,v 1.1 2008/07/14 20:42:41 sthen Exp $
--- xmlmemory.h.orig	Mon Jul 14 11:32:42 2008
+++ xmlmemory.h	Mon Jul 14 11:32:54 2008
@@ -14,6 +14,9 @@
 #ifdef HAVE_MALLOC_H
 #include <malloc.h>
 #endif
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
 
 #define xmlFree(x) free((x))
 #define xmlMalloc(x) malloc(x)