'config.h' is meant to be a convenience header to be #included at build
time, but not installed. Installing it can cause a host of problems for
various other projects (for instance, attempting to build u-boot from
source while another project's 'config.h' exists in the compiler search
path will cause build failures similar to:
https://github.com/pepe2k/u-boot_mod/issues/148



Further, I've changed '#include <config.h>' to '#include "config.h"',
which should constrain the search path to the current build directories,
so if another package with a bugged build has this file installed, it
will not cause yaml to miscompile/fail.

If you have a file `/usr/include/config.h` on your filesystem, query
your package manager to find out what package owns it, and file a bug
report against it with your distro maintainers.

Signed-off-by: Marty E. Plummer <hanetzer@protonmail.com>