adjust clientAddress in FORWARD_QUERY messages

- when the client address is a local address, it should not be
  placed in the FORWARD_QUERY message because it may be a loopback
  or link-local (or other non-global scope) address that cannot be
  contacted by the manager to which the FORWARD_QUERY message is
  sent.  X :%d -indirect localhost can generate this situation
  easily.

  Therefore, what XDM now does is, when the client address is local,
  it adjusts the clientAddress in the FORWARD_QUERY message to be
  the address that will be used to send the FORWARD_QUERY message
  to the manager instead of the origin of the INDIRECT_QUERY.
  When the client address is non-local, it is not adjusted.