bemxio [1] filed a deletion request for mingw-w64-headers-xp [2]: After a bit of more research after submitting the package, I found out `--with-default-win32-winnt` doesn't really make much difference.
[1] https://aur.archlinux.org/account/bemxio/ [2] https://aur.archlinux.org/pkgbase/mingw-w64-headers-xp/
