OS-2366 ddi_periodic_add(9F) is entirely rubbish

*** 19,28 ****
--- 19,29 ----
  # CDDL HEADER END
  #
  #
  # Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  # Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved.
+ # Copyright (c) 2013, Joyent, Inc.  All rights reserved.
  #
  
  #
  # This file simply contains the list of sources files compiled together
  # to create the genunix mdb module.   Having them in one place saves
*** 37,46 ****
--- 38,48 ----
          cpupart.c       \
          cred.c          \
          ctxop.c         \
          cyclic.c        \
          damap.c         \
+         ddi_periodic.c  \
          devinfo.c       \
          dist.c          \
          findstack.c     \
          findstack_subr.c \
          fm.c            \