12310 Add demangle(1) command

@@ -19,11 +19,11 @@
 # CDDL HEADER END
 #
 
 #
 # Copyright (c) 1989, 2010, Oracle and/or its affiliates. All rights reserved.
-# Copyright (c) 2019, Joyent, Inc.
+# Copyright 2019 Joyent, Inc.
 # Copyright (c) 2012, 2015 by Delphix. All rights reserved.
 # Copyright (c) 2013 DEY Storage Systems, Inc. All rights reserved.
 # Copyright 2014 Garrett D'Amore <garrett@damore.org>
 # Copyright 2016 Toomas Soome <tsoome@me.com>
 # Copyright 2018 Nexenta Systems, Inc.

@@ -116,10 +116,11 @@
         ctwatch         \
         datadm          \
         date            \
         dc              \
         dd              \
+        demangle        \
         deroff          \
         devfsadm        \
         syseventd       \
         devctl          \
         devinfo         \