Support exception rebinding.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/constructors_with_record2@14530 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Distinguish explicitly representation of regular records and inlined records with tag = 0.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/constructors_with_record2@14531 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02