Fix doc for unmarshaled exception values and structural comparison.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14669 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
#6119: document that the set of values contained in a closure is not specified and how this impacts marshaling references captured in closures, for instance.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14670 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02