add gentoo_variant detection and SYSCONFIG setup
add gentoo_variant detection and SYSCONFIG setup

duarten/scylla,duarten/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,avikivity/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,avikivity/scylla