bump sysctl interface version after c/s 23995:8943a9696358

That c/s made binary incompatible changes to struct pm_cx_stat.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -34,7 +34,7 @@
 #include "xen.h"
 #include "domctl.h"
 
-#define XEN_SYSCTL_INTERFACE_VERSION 0x00000008
+#define XEN_SYSCTL_INTERFACE_VERSION 0x00000009
 
 /*
  * Read console content from Xen buffer ring.