$NetBSD: patch-ae,v 1.4 2014/05/14 20:21:19 bouyer Exp $
- protect Xen's stdarg.h from multiple inclusion.
- build fix for stdarg under NetBSD.

Both backported from upstream.

http://xenbits.xensource.com/hg/xen-unstable.hg/file/a574bf2f5059/xen/include/xen/stdarg.h
--- xen/include/xen/stdarg.h.orig	2008-04-25 15:03:12.000000000 +0200
+++ xen/include/xen/stdarg.h	2014-05-14 16:11:10.000000000 +0200
@@ -1,5 +1,26 @@
+#ifndef __XEN_STDARG_H__
+#define __XEN_STDARG_H__
+
 #if defined(__OpenBSD__)
 #  include "/usr/include/stdarg.h"
+#elif defined (__NetBSD__)
+#ifdef __GNUC__
+#define __GNUC_PREREQ__(x, y)						\
+	((__GNUC__ == (x) && __GNUC_MINOR__ >= (y)) ||			\
+	 (__GNUC__ > (x)))
+#else
+#define __GNUC_PREREQ__(x, y)	0
+#endif
+   typedef __builtin_va_list va_list;
+#if __GNUC_PREREQ__(4, 5)
+#  define va_start(ap, last)	__builtin_va_start((ap), (last))
+#else
+#  define va_start(ap, last)    __builtin_stdarg_start((ap), (last))
+#endif /* __GNUC_PREREQ__ */
+#  define va_end(ap)            __builtin_va_end(ap)
+#  define va_arg                __builtin_va_arg
 #else
 #  include <stdarg.h>
 #endif
+
+#endif /* __XEN_STDARG_H__ */