PR#6418: support "@[<hov %d>" in the new format implementation (Benoît Vaugon)
    
    The bootstrap procedure, as for commit 4.02@14975 (see there for
    detailed build instructions), requires to first commit a temporary
    patch:
    
    > diff -Naur old/typing/typecore.ml new/typing/typecore.ml
    > --- old/typing/typecore.ml        2014-06-11 18:16:24.851647309 +0200
    > +++ new/typing/typecore.ml        2014-06-11 18:15:50.075646418 +0200
    > @@ -2758,16 +2758,9 @@
    >        let mk_int n = mk_cst (Const_int n)
    >        and mk_string str = mk_cst (Const_string (str, None))
    >        and mk_char chr = mk_cst (Const_char chr) in
    > -      let mk_block_type bty = match bty with
    > -        | Pp_hbox   -> mk_constr "Pp_hbox"   []
    > -        | Pp_vbox   -> mk_constr "Pp_vbox"   []
    > -        | Pp_hvbox  -> mk_constr "Pp_hvbox"  []
    > -        | Pp_hovbox -> mk_constr "Pp_hovbox" []
    > -        | Pp_box    -> mk_constr "Pp_box"    []
    > -        | Pp_fits   -> mk_constr "Pp_fits"   [] in
    >        let rec mk_formatting_lit fmting = match fmting with
    > -        | Open_box (org, bty, idt) ->
    > -          mk_constr "Open_box" [ mk_string org; mk_block_type bty; mk_int idt ]
    > +        | Open_box _ ->
    > +          assert false
    >          | Close_box ->
    >            mk_constr "Close_box" []
    >          | Close_tag ->
    > @@ -2950,6 +2943,19 @@
    >            mk_constr "Alpha" [ mk_fmt rest ]
    >          | Theta rest ->
    >            mk_constr "Theta" [ mk_fmt rest ]
    > +        | Formatting_lit (Open_box (org, _bty, _idt), rest) ->
    > +          mk_constr "Formatting_gen" [
    > +            mk_constr "Open_box" [
    > +              mk_constr "Format" [
    > +                mk_constr "String_literal" [
    > +                  mk_string "<>";
    > +                  mk_constr "End_of_format" [];
    > +                ];
    > +                mk_string "@[<>";
    > +              ]
    > +            ];
    > +            mk_fmt rest;
    > +          ]
    >          | Formatting_lit (fmting, rest) ->
    >            mk_constr "Formatting_lit" [ mk_formatting_lit fmting; mk_fmt rest ]
    >          | Formatting_gen (fmting, rest) ->
    
    git-svn-id: http://caml.inria.fr/svn/ocaml/version/4.02@14985 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02