<KHR/khrplatform.h> not found on OpenBSD, alpinelinux and others?
See https://github.com/haasn/libplacebo/issues/246

Not sure what's going on here, it seems that this header does not exist on some platforms. Maybe it needs to be made conditional somehow. The issue poster over there suggests extracting the include path from `gl.pc`, but I am not convinced this is the best solution.