Empty ident is not allowed.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/constructors_with_record5@15547 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Accept changes.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/constructors_with_record5@15548 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02