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.
Obsolete, fixed some time ago: https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=a98cf70c310e8b824b1ffc1259056302a1732dc2