There is an updated ebuild for libxsd-frontend-2.0.0 available in the esteid overlay at https://github.com/urmet/esteid-overlay/tree/master/dev-cpp/libxsd-frontend, more specifically, https://github.com/urmet/esteid-overlay/blob/3c8559368f51a6e1efc14e3bdf5fca11650e30bc/dev-cpp/libxsd-frontend/libxsd-frontend-2.0.0.ebuild It is needed for the Estonian ID-card infrastructure.
commit 10adf90b3ef081369f26aa6d6b57787447ff11cb Author: David Seifert <soap@gentoo.org> Date: Sat Oct 15 15:40:39 2016 +0200 dev-cpp/libxsd-frontend: Version bump to 2.0.0 Gentoo-bug: 585738, 594542 * EAPI=6