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

@@ -471,11 +471,11 @@
                  * the insertion point is immediately before seg.
                  */
                 if (base + seg->s_size > addr) {
                         if (addr >= base || eaddr > base) {
 #ifdef __sparc
-                                extern struct seg_ops segnf_ops;
+                                extern const struct seg_ops segnf_ops;
 
                                 /*
                                  * no-fault segs must disappear if overlaid.
                                  * XXX need new segment type so
                                  * we don't have to check s_ops

@@ -2003,11 +2003,11 @@
  * We're lazy and only return one segment at a time.
  */
 int
 as_memory(struct as *as, caddr_t *basep, size_t *lenp)
 {
-        extern struct seg_ops segspt_shmops;    /* needs a header file */
+        extern const struct seg_ops segspt_shmops;      /* needs a header file */
         struct seg *seg;
         caddr_t addr, eaddr;
         caddr_t segend;
 
         AS_LOCK_ENTER(as, &as->a_lock, RW_READER);

@@ -2480,11 +2480,11 @@
         page_t **pl;
         int error;
         caddr_t eaddr;
         faultcode_t fault_err = 0;
         pgcnt_t pl_off;
-        extern struct seg_ops segspt_shmops;
+        extern const struct seg_ops segspt_shmops;
 
         ASSERT(AS_LOCK_HELD(as, &as->a_lock));
         ASSERT(seg != NULL);
         ASSERT(addr >= seg->s_base && addr < seg->s_base + seg->s_size);
         ASSERT(addr + size > seg->s_base + seg->s_size);