Anyway, I'll have a go at updating gaur to use 4.5.x. There is a sane-looking stdint.h on my second-oldest dinosaur, prairiedog. Don't know about the situation on Windows, though. We might want to take a close look at NetBSD, too, based on the GCC notes.
As for Windows, stdint.h was included in VS2010, and currently Postgres supports VS2013 to 2019.