3373 gcc >= 4.5 concerns about offsetof()

*** 146,156 ****
   * Introduce an index into the list to speed up insert_into looking for the
   * right position in the list. This index is an AVL tree of all the
   * iodev_snapshot in the list.
   */
  
! #define offsetof(s, m)  (size_t)(&(((s *)0)->m))        /* for avl_create */
  
  static int
  avl_iodev_cmp(const void* is1, const void* is2)
  {
          int c = iodev_cmp((struct iodev_snapshot *)is1,
--- 146,160 ----
   * Introduce an index into the list to speed up insert_into looking for the
   * right position in the list. This index is an AVL tree of all the
   * iodev_snapshot in the list.
   */
  
! #if defined(__GNUC__)
! #define offsetof(s, m)  __builtin_offsetof(s, m)
! #else
! #define offsetof(s, m)  ((size_t)(&(((s *)0)->m)))      /* for avl_create */
! #endif
  
  static int
  avl_iodev_cmp(const void* is1, const void* is2)
  {
          int c = iodev_cmp((struct iodev_snapshot *)is1,