3373 gcc >= 4.5 concerns about offsetof()

*** 24,42 ****
   */
  
  #ifndef _MDBMOD_MISC_H
  #define _MDBMOD_MISC_H
  
- #pragma ident   "%Z%%M% %I%     %E% SMI"
- 
  #include <mdb/mdb_modapi.h>
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  #define offsetof(s, m)  ((size_t)(&(((s *)0)->m)))
  
  extern int umem_debug(uintptr_t, uint_t, int, const mdb_arg_t *);
  
  extern int umem_set_standalone(void);
  extern ssize_t umem_lookup_by_name(const char *, GElf_Sym *);
--- 24,44 ----
   */
  
  #ifndef _MDBMOD_MISC_H
  #define _MDBMOD_MISC_H
  
  #include <mdb/mdb_modapi.h>
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
+ #if defined(__GNUC__)
+ #define offsetof(s, m)  __builtin_offsetof(s, m)
+ #else
  #define offsetof(s, m)  ((size_t)(&(((s *)0)->m)))
+ #endif
  
  extern int umem_debug(uintptr_t, uint_t, int, const mdb_arg_t *);
  
  extern int umem_set_standalone(void);
  extern ssize_t umem_lookup_by_name(const char *, GElf_Sym *);