#5528: type extensions can create local type names t.A without an explicit local type t (if the extended type is non-local).  We must thus check explicitly uniqueness of synthesized type names t.A instead of relying on uniqueness of declared types as before (well, we already had the problem if someone redefined a local exn type).

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/constructors_with_record3@15083 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Accept test result.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/constructors_with_record3@15084 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Bug is fixed.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/constructors_with_record3@15085 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02