Make the node processor and the pattern writer track the current
compositing color state. Color state nodes change it. We pass
the surface color state down via the frame apis.
The name of the variable is "ccs" for "compositing color space". It's an
unused variable name and it's common enough to deserve a short and sweet
name.
We import them as general, so they should be exported like that.
This was a longstanding issue that I never got around to fixing and I'm
touching this code anyway atm.
See commit 3aa6c27c26 for more details.
For now, it just renders using cairo, uploads the result to the GPU,
blits it onto the framebuffer and then is happy.
But it can do that using Vulkan and using GL (no idea which version).
The most important thing still missing is shaders.
It also has a bunch of copy/paste from the Vulkan renderer that isn't
used yet.
But I didn't want to rip it out and then try to copy it back later
