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

@@ -136,11 +136,11 @@
 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 = {
+static const struct seg_ops segkp_ops = {
         .fault          = segkp_fault,
         .checkprot      = segkp_checkprot,
         .kluster        = segkp_kluster,
         .dump           = segkp_dump,
         .pagelock       = segkp_pagelock,