OS-2366 ddi_periodic_add(9F) is entirely rubbish

*** 20,30 ****
   */
  
  /*
   * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
!  * Copyright 2011 Joyent, Inc.  All rights reserved.
   */
  
  #include <sys/param.h>
  #include <sys/types.h>
  #include <sys/sysmacros.h>
--- 20,30 ----
   */
  
  /*
   * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
!  * Copyright 2013 Joyent, Inc.  All rights reserved.
   */
  
  #include <sys/param.h>
  #include <sys/types.h>
  #include <sys/sysmacros.h>
*** 46,55 ****
--- 46,56 ----
  #include <sys/debug.h>
  #include <sys/ftrace.h>
  #include <sys/cmn_err.h>
  #include <sys/panic.h>
  #include <sys/ddi.h>
+ #include <sys/ddi_periodic.h>
  #include <sys/sunddi.h>
  #include <sys/policy.h>
  #include <sys/zone.h>
  #include <sys/condvar.h>
  #include <sys/thread.h>
*** 283,292 ****
--- 284,299 ----
  
                  vfs_unmountall();
                  (void) VFS_MOUNTROOT(rootvfs, ROOT_UNMOUNT);
                  vfs_syncall();
  
+                 /*
+                  * Check for (and unregister) any DDI periodic handlers that
+                  * still exist, as they most likely constitute resource leaks:
+                  */
+                 ddi_periodic_fini();
+ 
                  dump_ereports();
                  dump_messages();
  
                  invoke_cb = B_TRUE;