DEFINE_XEN_GUEST_HANDLE is evaluated by the pre-processor twice. Do this also for XEN_GUEST_HANDLE.

This fixes a build error for PV guests (OpenBSD, NetBSD) where the use
of XEN_GUEST_HANDLE(uint8_t) leads to a build error because uint8_t is
a #define instead a typedef.

Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>

xen/include/public/arch-x86/xen.h

@@ -37,7 +37,8 @@
 #endif
 
 #define DEFINE_XEN_GUEST_HANDLE(name)   __DEFINE_XEN_GUEST_HANDLE(name, name)
-#define XEN_GUEST_HANDLE(name)          __guest_handle_ ## name
+#define __XEN_GUEST_HANDLE(name)        __guest_handle_ ## name
+#define XEN_GUEST_HANDLE(name)          __XEN_GUEST_HANDLE(name)
 #define set_xen_guest_handle(hnd, val)  do { (hnd).p = val; } while (0)
 #ifdef __XEN_TOOLS__
 #define get_xen_guest_handle(val, hnd)  do { val = (hnd).p; } while (0)