2976 remove useless offsetof() macros

*** 34,53 ****
  
  #if defined(_KERNEL) && !defined(_BOOT)
  #include <sys/varargs.h>
  #include <sys/ddi.h>
  #include <sys/sunddi.h>
  #else
  #include <stdarg.h>
  #include <stdlib.h>
  #include <string.h>
  #include <strings.h>
  #endif
  
- #ifndef offsetof
- #define offsetof(s, m)          ((size_t)(&(((s *)0)->m)))
- #endif
  #define skip_whitespace(p)      while ((*(p) == ' ') || (*(p) == '\t')) p++
  
  /*
   * nvpair.c - Provides kernel & userland interfaces for manipulating
   *      name-value pairs.
--- 34,52 ----
  
  #if defined(_KERNEL) && !defined(_BOOT)
  #include <sys/varargs.h>
  #include <sys/ddi.h>
  #include <sys/sunddi.h>
+ #include <sys/sysmacros.h>
  #else
  #include <stdarg.h>
  #include <stdlib.h>
  #include <string.h>
  #include <strings.h>
+ #include <stddef.h>
  #endif
  
  #define skip_whitespace(p)      while ((*(p) == ' ') || (*(p) == '\t')) p++
  
  /*
   * nvpair.c - Provides kernel & userland interfaces for manipulating
   *      name-value pairs.