We *always* generate this file, and we depend on its existence.
The idea behind HAVE_CONFIG_H was being able to include random files
from different projects, back in a time where "libraries" were literally
just random files instead of actual shared objects.
Since we're not in the '80s any more, and our build system(s) define
HAVE_CONFIG_H *and* generate the config.h header file, we don't need a
conditional guard around its inclusion.
A very simple surface that produces a hierarchical DAG in a simple XML
format. It is intended to be used whilst debugging, for example with the
automatic regression finding tools of cairo-sphinx, and with test suites
that just want to verify that their code made a particular Cairo call.