Fix the Camlp4 tutorial for 4.03.0

[Chris00]

https://ocaml.org/learn/tutorials/camlp4_3.10/foreach_tutorial.html shows

# #load "camlp4o.cma";;
File "", line 1:
Error: Reference to undefined global `Sort'
# (* Add directory where the syntax extension is compiled to the module
     path (not required if pa_foreach.cmo is in the current directory). *)
  #directory "site/learn/tutorials/camlp4_3.10/";;
# #load "pa_foreach.cmo";;
File "", line 1:
Error: Reference to undefined global `Camlp4'
# for s in

 List ["hello"; "world"] do print_endline s done;;
Error: Syntax error