Bugfix: config.h shouldn't be installed.

Bugfix: config.h shouldn't be installed.

The pre-generated config.h shouldn't be installed by default.
This fixes some mistakes in: "106c18c3 Feature: Enable config.h, config.c, and config.cpp support in package generation.".

The source files and any potential headers may still need changes to properly include the config.h as necessary.
Still, this is a step forward in making this project friendlier with some existing practices, even if it is only half a step.