use NULL capable segop as a shorthand for no-capabilities
Instead of forcing every segment driver to implement a dummy "return 0"
function, handle NULL capable segop function pointer as "no copabilities
supported" shorthand.

*** 110,120 ****
  static int segspt_shmpagelock(struct seg *, caddr_t, size_t,
                          struct page ***, enum lock_type, enum seg_rw);
  static int segspt_shmsetpgsz(struct seg *, caddr_t, size_t, uint_t);
  static int segspt_shmgetmemid(struct seg *, caddr_t, memid_t *);
  static lgrp_mem_policy_info_t *segspt_shmgetpolicy(struct seg *, caddr_t);
- static int segspt_shmcapable(struct seg *, segcapability_t);
  
  struct seg_ops segspt_shmops = {
          .dup            = segspt_shmdup,
          .unmap          = segspt_shmunmap,
          .free           = segspt_shmfree,
--- 110,119 ----
*** 134,144 ****
          .dump           = segspt_shmdump,
          .pagelock       = segspt_shmpagelock,
          .setpagesize    = segspt_shmsetpgsz,
          .getmemid       = segspt_shmgetmemid,
          .getpolicy      = segspt_shmgetpolicy,
-         .capable        = segspt_shmcapable,
  };
  
  static void segspt_purge(struct seg *seg);
  static int segspt_reclaim(void *, caddr_t, size_t, struct page **,
                  enum seg_rw, int);
--- 133,142 ----
*** 3045,3056 ****
          anon_index = seg_page(seg, addr);
          policy_info = lgrp_shm_policy_get(amp, anon_index, NULL, 0);
  
          return (policy_info);
  }
- 
- /*ARGSUSED*/
- static int
- segspt_shmcapable(struct seg *seg, segcapability_t capability)
- {
-         return (0);
- }
--- 3043,3047 ----