6151 use NULL setpagesize segop as a shorthand for ENOTSUP

*** 1975,1984 ****
--- 1975,1987 ----
  }
  
  int
  segop_setpagesize(struct seg *seg, caddr_t addr, size_t len, uint_t szc)
  {
+         if (seg->s_ops->setpagesize == NULL)
+                 return (ENOTSUP);
+ 
          return (seg->s_ops->setpagesize(seg, addr, len, szc));
  }
  
  int
  segop_getmemid(struct seg *seg, caddr_t addr, memid_t *mp)