CentOS 7.4 does support to use ambient capabilities on systemd unit file, but on some other RHEL7 compatible enviroment doesn't, it causes Scylla startup failure. To avoid the issue, move AmbientCapabilities line to /etc/systemd/system/scylla.server.service.d/, install .conf only when both systemd and kernel supported the feature. Fixes #3486 Signed-off-by: Takuya ASADA <syuu@scylladb.com> Message-Id: <20180613232327.7839-1-syuu@scylladb.com>