Use OCAMLPARAM's objects in toplevel

Only the non-native one (it does not support OCAMLPARAM at all atm).

driver/compenv.mli

@@ -32,6 +32,8 @@ val implicit_modules : string list ref
 
 (* return the list of objfiles, after OCAMLPARAM and List.rev *)
 val get_objfiles : with_ocamlparam:bool -> string list
+val last_objfiles : string list ref
+val first_objfiles : string list ref
 
 type filename = string
 

toplevel/topmain.ml

@@ -25,7 +25,11 @@ let prepare ppf =
   Toploop.set_paths ();
   try
     let res =
-      List.for_all (Topdirs.load_file ppf) (List.rev !preload_objects) in
+      let objects =
+        List.rev (!preload_objects @ !first_objfiles)
+      in
+      List.for_all (Topdirs.load_file ppf) objects
+    in
     !Toploop.toplevel_startup_hook ();
     res
   with x ->