Attempting to install the latest ebuild from mabi's overlay resulted in failure with lots of complaints about /usr/lib64. Looking at the ebuild, it seems like there is LIBDIR=/usr/$(get_libdir) in the make, but not make install. There's no good reason for it to be necessary in both places, but it not being in the make install seems to break it.
I'm still wondering what this libdir thing is about, but anyway - hopefully fixed by adding another LIBDIR in src_install Thanks for the report