sd-nework: be more careful with error codes, return ENODATA if you lack information
networkctl: two OOM fixes
networkd: remove "*" from domains list

Also, simplify things a bit and make sure we don't forget looking at one
of the entries.
networkd: always write out locally configured settings first, dhcp-acquired ones later

This is primarily important for the domains list, as we really should
prefer the locally configured domain over the dhcp supplied ones when we
use it as a search list.