Today in "why did we ever do this?", we discover we've vendored
code from PIL/Pillow, but PIL/Pillow moved some macro definitions
around, so now our vendored code conflicted with their macros that
they included in the headers we're including.
The solution is to throw out our vendored macros and update the
semantics in our vendored Draw.c. I'm not sure why we vendored it,
but we seemingly did remove some stuff from it to avoid having to
pull in all of PIL/Pillow.