PR#5644: a dumbed-down fix to fix the observable effect (Stream.of_string) with no change to the underlying code (to avoid regressions)
    
    As I learned the hard way, it is essentially impossible to get
    a satisfying behavior in presence of a mix of updates, concatenations
    and counts. The best thing to do is thus to not change anything
    (a good way to preserve compatibility), and only fix the
    Stream.of_string function to assume nothing of the count passed to the
    [from] function.
    
    I also modified the mli documentation of [Stream.from] to warn other
    users of this potential pitfall.
    
    
    git-svn-id: http://caml.inria.fr/svn/ocaml/version/4.01@13917 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02