Please check whether the use of 'einstall' in this ebuild is actually needed. From a quick glance at the Makefile, it seems to have proper support for DESTDIR. Therefore, if possible please replace the call to 'einstall' with proper 'default' or 'emake DESTDIR="${D}" install'. Thanks.
commit ea17159739c98e2365d1ce3ad0d669d3dae6fdb7 Author: David Seifert <soap@gentoo.org> Date: Sat Jan 23 17:29:00 2016 +0100 media-sound/splay: Remove use of 'einstall', EAPI=6 Gentoo-Bug: 521566