Add libifc, a library implementing core functionality that exists in ifconfig(8) today.
libifc (pronounced lib-ifconfig) aims to be a light abstraction layer between
programs and the kernel APIs for managing the network configuration.
This should hopefully make programs easier to maintain, and reduce code
Work will begin on making ifconfig(8) use this library in the near future.
This code is still evolving. The interface should not be considered stable until
it is announced as such.
Submitted By: Marie Helene Kvello-Aune <email@example.com>
Reviewed By: kp
Differential Revision: https://reviews.freebsd.org/D7529