Gentoo libretro overlay.
To use the overlay, add this in /etc/portage/repos.conf/retroverlay.conf:
[retroverlay]
location = /var/portage/retroverlay
sync-type = git
sync-uri = https://github.com/gen2brain/gentoo-retroverlay.git
masters = gentoo
auto-sync = yes