2976 remove useless offsetof() macros

*** 31,40 ****
--- 31,41 ----
  #include <sys/conf.h>
  #include <sys/cmn_err.h>
  #include <sys/modctl.h>
  #include <sys/cred.h>
  #include <sys/ddi.h>
+ #include <sys/sysmacros.h>
  #include <sys/unistat/spcs_s.h>
  #include <sys/unistat/spcs_s_k.h>
  #include <sys/unistat/spcs_errors.h>
  
  #include <sys/nsc_thread.h>
*** 519,536 ****
          }
  
          return (0);
  }
  
- 
- /*
-  * Yet another standard thing that is not standard ...
-  */
- #ifndef offsetof
- #define offsetof(s, m)  ((size_t)(&((s *)0)->m))
- #endif
- 
  /*
   * Build a 32bit rdc_set structure and copyout to the user level.
   */
  int
  rdc_status_copy32(const void *arg, void *usetp, size_t size, int mode)
--- 520,529 ----