re #13613 rb4516 Tunables needs volatile keyword

*** 21,30 ****
--- 21,33 ----
  
  /*
   * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
+ /*
+  * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
+  */
  
  /*
   * Copyright (c) 2015, Joyent, Inc. All rights reserved.
   */
  
*** 40,50 ****
  #endif
  
  #ifdef  _KERNEL
  
  #define _TIMER_MAX      32
! extern  int     timer_max;              /* patchable via /etc/system */
  
  /*
   * Bit values for the it_lock field.
   */
  #define ITLK_LOCKED             0x01
--- 43,53 ----
  #endif
  
  #ifdef  _KERNEL
  
  #define _TIMER_MAX      32
! extern  volatile int    timer_max;      /* patchable via /etc/system */
  
  /*
   * Bit values for the it_lock field.
   */
  #define ITLK_LOCKED             0x01