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

*** 136,146 ****
  uint32_t        red_ndoubles;
  
  pgcnt_t anon_segkp_pages_locked;        /* See vm/anon.h */
  pgcnt_t anon_segkp_pages_resv;          /* anon reserved by seg_kp */
  
! static struct   seg_ops segkp_ops = {
          .fault          = segkp_fault,
          .checkprot      = segkp_checkprot,
          .kluster        = segkp_kluster,
          .dump           = segkp_dump,
          .pagelock       = segkp_pagelock,
--- 136,146 ----
  uint32_t        red_ndoubles;
  
  pgcnt_t anon_segkp_pages_locked;        /* See vm/anon.h */
  pgcnt_t anon_segkp_pages_resv;          /* anon reserved by seg_kp */
  
! static const struct seg_ops segkp_ops = {
          .fault          = segkp_fault,
          .checkprot      = segkp_checkprot,
          .kluster        = segkp_kluster,
          .dump           = segkp_dump,
          .pagelock       = segkp_pagelock,