config: test that fields of keyed structs are properly pointered
config: test that fields of keyed structs are properly pointered

Check the fields that affect the key function of a keyed struct to
ensure that non-pointer primitive fields are part of the key, and there
is at least one of them.  Add exceptions for places where we currently
get this wrong.

coreos/ignition,coreos/ignition,coreos/ignition