>=dev-libs/wayland-protocols-1.5 dropped multilib per bug 587842.
Go ahead please
commit 6ffcbd2d1594fbf4be76d751b56e07918e808796 Author: Chí-Thanh Christopher Nguyễn <chithanh@gentoo.org> Date: Sun Jul 24 15:10:20 2016 +0200 x11-libs/gtk+: remove multilib dependency on dev-libs/wayland-protocols Bug: https://bugs.gentoo.org/show_bug.cgi?id=589584