Adding ifam_pid to ifa_msghdr

[Roy Marples <roy%marples.name@localhost>]

Hi List!

Unlike rtm_msghdr, ifam_msghdr has no idea of the identity of the process who 
added or deleted an address.

This is important for processes which add/delete addresses while listening for 
3rd parties to add/delete addresses as well, so self generated messages can be 
ignored.

Here is a simple patch which adds ifam_pid to ifa_msghdr so the identity of 
the sender is known.
http://www.netbsd.org/~roy/ifam_pid.patch

Unless anyone objects, I will add this soon.

Roy