- The ai_addrlen of a struct addrinfo used to be a size_t, per

- The ai_addrlen of a struct addrinfo used to be a size_t, per
  RFC 2553.  In XNS5.2, and subsequently in POSIX-2001 and RFC
  3493, it was changed to a socklen_t.  And, the n_net of a
  struct netent used to be an unsigned long integer.  In XNS5,
  and subsequently in POSIX-2001, it was changed to an uint32_t.
  To accomodate for this while preserving ABI compatibility with
  the old interface, we need to prepend or append 32 bits of
  padding, depending on the (LP64) architecture's endianness.
- Correct 1st argument of getnetbyaddr() to uint32_t on 32
  bit arch.  Stay as is on 64 bit arch for ABI backward
  compatibility for now.

Reviewed by:	das, peter
MFC after:	2 weeks