Handle the case of systemd-resolved, and if in place
use a different resolv.conf source.
Set appropriately the option on libnetwork.
Move unix specific code to container_operation_unix
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
Upstream-commit: e353e7e3f0ce8eceeff657393cba2876375403fa
Component: engine
1d8c80a782