Do not register labels of inlined records into the environment; they can only be used through type-based selection.  Silence out-of-scope and disambiguated warnings when they are selected.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/constructors_with_record3@14638 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02