re #13613 rb4516 Tunables needs volatile keyword

*** 342,352 ****
   * Automagic pageout.
   * When memory gets tight, start freeing pages popping out of the
   * write queue.
   */
  int     write_free = 1;
! pgcnt_t pages_before_pager = 200;       /* LMXXX */
  
  /*
   * Routine to be called when page-out's complete.
   * The caller, typically VOP_PUTPAGE, has to explicity call this routine
   * after waiting for i/o to complete (biowait) to free the list of
--- 342,352 ----
   * Automagic pageout.
   * When memory gets tight, start freeing pages popping out of the
   * write queue.
   */
  int     write_free = 1;
! volatile pgcnt_t pages_before_pager = 200;      /* LMXXX */
  
  /*
   * Routine to be called when page-out's complete.
   * The caller, typically VOP_PUTPAGE, has to explicity call this routine
   * after waiting for i/o to complete (biowait) to free the list of