Fix compilation since machine/xen/xen-os.h is requiring definition
existing in xen/xen-os.h.
In general machine/xen/xen-os.h should never be included
#include <sys/sx.h>
#include <sys/taskqueue.h>
-#include <machine/xen/xen-os.h>
#include <machine/stdarg.h>
+#include <xen/xen-os.h>
#include <xen/gnttab.h>
#include <xen/xenstore/xenstorevar.h>
#include <xen/xenbus/xenbusb.h>
#include <sys/sx.h>
#include <sys/taskqueue.h>
-#include <machine/xen/xen-os.h>
#include <machine/stdarg.h>
+#include <xen/xen-os.h>
#include <xen/gnttab.h>
#include <xen/xenbus/xenbusvar.h>
#include <xen/xenbus/xenbusb.h>