Sure, how about something like MR !9461?
Yes. (Only nitpick is that there should be more comments explaining the why.)
Any other variables we should add there?
Nothing comes to mind. More can always be added later.
Should we ignore all the SDL_ variables?
Wine and forks only use them through `getenv` imported from `<stdlib.h>`, so it shouldn't matter whether they are in the Windows environment if I'm correct.