const-ify make segment ops structures
There is no reason to keep the segment ops structures writable.

*** 95,106 ****
          ulong_t pg_pnbase;      /* pn within segment of first protv element */
  } prpagev_t;
  
  size_t pagev_lim = 256 * 1024;  /* limit on number of pages in prpagev_t */
  
! extern struct seg_ops segdev_ops;       /* needs a header file */
! extern struct seg_ops segspt_shmops;    /* needs a header file */
  
  static  int     set_watched_page(proc_t *, caddr_t, caddr_t, ulong_t, ulong_t);
  static  void    clear_watched_page(proc_t *, caddr_t, caddr_t, ulong_t);
  
  /*
--- 95,106 ----
          ulong_t pg_pnbase;      /* pn within segment of first protv element */
  } prpagev_t;
  
  size_t pagev_lim = 256 * 1024;  /* limit on number of pages in prpagev_t */
  
! extern const struct seg_ops segdev_ops; /* needs a header file */
! extern const struct seg_ops segspt_shmops;      /* needs a header file */
  
  static  int     set_watched_page(proc_t *, caddr_t, caddr_t, ulong_t, ulong_t);
  static  void    clear_watched_page(proc_t *, caddr_t, caddr_t, ulong_t);
  
  /*