This needs to be updated to 5.16, the URL is invalid on all of the possible proxy sites and the package fails to build, it does however build if moved to 5.16. This appears to be an upkeep issue.
Please make sure you have a valid GENTOO_MIRRORS.
thank you, my appologies, i have been bouncing around too many different incarnations of gentoo to make sure my make.conf was updated. Please forgive me. not a bug, just a version bump request.