Based on the orginal patch by oldfashionedcow to add the abilty for
a user to set a custom kconfig for their livecd to be moved to
/etc/kernel/config.d/ before sys-kernel/gentoo-kernel is emerged.

Syntax is the same as the one used for Genkernel kconfigs.

Closes: https://bugs.gentoo.org/936676



Co-authored-by: Rahul Sandh <rahul@sandhuservices.dev>
Co-authored-by: Christopher Fore <csfore@posteo.net>

Signed-off-by: Ian Jordan <immoloism@gmail.com>
Closes: https://github.com/gentoo/catalyst/pull/21


Signed-off-by: Ben Kohler <bkohler@gentoo.org>