It just had one macro, and that macro only used where isc/error.h
is used.

isc/sockaddr.h is the only place ISC_LINK() was needed.

Unused header.

isc/netaddr.h included isc/net.h and they were always used together.

isc/netaddr.h is where they are used.

Put them in isc/interfaceiter.h where they are used.

isc/reulst.h is where it is used.

The few bits in isc/types.h already move to better places.