#6688: allow val declarations as structure items.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15645 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
#6688: fix comment.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15646 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02