privsep: Detect a suitable user for dhcpcd, otherwise use dhcpcd
privsep: Detect a suitable user for dhcpcd, otherwise use dhcpcd

System users generally have _ preceeding their username.
Only use this user if it exists and their home dir is not /var/empty.
Otherwise default to using dhcpcd.

rsmarples/dhcpcd,rsmarples/dhcpcd,rsmarples/dhcpcd