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.
We define _GNU_SOURCE globally in both the Autotools build, through the
use of the AC_USE_SYSTEM_EXTENSIONS macro; and in the Meson build, with
add_project_arguments().
This is a simple variation on cairo-trace that wraps records the last 16
contexts by wrapping the target surface inside a tee surface, along with a
meta/recording surface. Then on receipt of a SIGUSR1, those last 16
contexts are played via a script-surface into /tmp/fdr.trace.
Mostly proof-of-concept, it seems to be causing a number of rendering
glitches whilst testing with firefox -- otherwise, it seems to works.
