12071 clarify implementation of single_instance in SMF services
Reviewed by: Robert Mustacchi <rm@fingolfin.org>

@@ -21,10 +21,11 @@
 /*
  * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 /*
  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
+ * Copyright 2019 Joyent, Inc.
  */
 
 
 /*
  * XML document manipulation routines

@@ -3315,13 +3316,16 @@
         }
 
         return (0);
 }
 
-/* ARGSUSED1 */
+/*
+ * Unimplemented and obsolete, but we still process it for compatibility
+ * purposes.
+ */
 static int
-lxml_get_single_instance(entity_t *entity, xmlNodePtr si)
+lxml_get_single_instance(entity_t *entity, xmlNodePtr si __unused)
 {
         pgroup_t *pg;
         property_t *p;
         int r;