xenapi: Add managedsave entries to the driver struct

Commit 15c647a9 added the new
managedsave entries to all driver structs except the XenAPI one.

src/xenapi/xenapi_driver.c

@@ -1783,6 +1783,9 @@ static virDriver xenapiDriver = {
     NULL, /* domainMigrateSetMaxDowntime */
     NULL, /* domainEventRegisterAny */
     NULL, /* domainEventDeregisterAny */
+    NULL, /* domainManagedSave */
+    NULL, /* domainHasManagedSaveImage */
+    NULL, /* domainManagedSaveRemove */
 };
 
 /**