re #13613 rb4516 Tunables needs volatile keyword

*** 18,29 ****
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
!  *
!  * Copyright 2011, 2012 Nexenta Systems, Inc. All rights reserved.
   * Copyright 2013 Joyent, Inc. All rights reserved.
   */
  
  /*
   * This is the loadable module wrapper.
--- 18,28 ----
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
   * Copyright 2013 Joyent, Inc. All rights reserved.
   */
  
  /*
   * This is the loadable module wrapper.
*** 59,71 ****
          &mod_fsops,
          "network filesystem version 4",
          &vfw4
  };
  
! uint_t nfs4_max_transfer_size = 32 * 1024;
! uint_t nfs4_max_transfer_size_cots = 1024 * 1024;
! uint_t nfs4_max_transfer_size_rdma = 1024 * 1024;
  
  int
  nfs4tsize(void)
  {
          /*
--- 58,70 ----
          &mod_fsops,
          "network filesystem version 4",
          &vfw4
  };
  
! volatile uint_t nfs4_max_transfer_size = 32 * 1024;
! volatile uint_t nfs4_max_transfer_size_cots = 1024 * 1024;
! volatile uint_t nfs4_max_transfer_size_rdma = 1024 * 1024;
  
  int
  nfs4tsize(void)
  {
          /*