Re-export Config.load_path as UTop.load_path

This change helps to implement toplevel extensions that want
to find files in the load path, e.g. for improved error messages.

src/lib/uTop.cppo.ml

@@ -732,6 +732,12 @@ let () =
   (* Make UTop accessible. *)
   Topdirs.dir_directory (Findlib.package_directory "utop")
 
+(* +-----------------------------------------------------------------+
+   | Compiler-libs re-exports                                        |
+   +-----------------------------------------------------------------+ *)
+
+let load_path = Config.load_path
+
 (* +-----------------------------------------------------------------+
    | Deprecated                                                      |
    +-----------------------------------------------------------------+ *)

src/lib/uTop.mli

@@ -303,6 +303,13 @@ val discard_formatters : Format.formatter list -> (unit -> 'a) -> 'a
 
 val split_words : string -> string list
 
+(** {6 compiler-libs reexports} *)
+
+val load_path : string list ref
+  (** [load_path] is an alias of [Config.load_path], normally hidden in toplevel.
+      It contains the list of directories added by findlib-required packages
+      and [#directory] directives. *)
+
 (**/**)
 
 (* These variables are not used and deprecated: *)