libkres-dev headers are brokens

[Jean-Daniel Dupas]

libkres-dev installed headers are designed to be used in the knot-resolver source tree and are unusable when installed in /usr/include.

These headers should either be removed completely or they should be patched to be usable from elsewhere (using #include <libkres/*> instead of #include "lib/*", and adding some headers that are #included by not distributed in the dev package).

[Vladimír Čunát (vcunat)]

We (upstream) are not aware of any existing or planned SW anywhere using the headers or libkres :-) (except kresd linking against libkres, of course)

[Jean-Daniel Dupas (xooloo)]

They are required to develop native kresd plugins(We need such plugin in our infrastructure, but I'm pretty sure very few people need that).
The distributed headers are completely unusable as they use double quotes instead of angle brackets and IIRC, they even reference headers that are not distributed in include (and require to use them from source directly).

They probably should not be distributed at all, but letting them here probably don't cause any arm.