build: use camlp-streams instead of deprecated Stdlib.Streams

lib/dune

 (library
  (name lutils)
  (public_name lutils)
- (libraries unix str num)
+ (libraries unix str num camlp-streams)
  (wrapped false)
  (synopsis "A lib shared by Verimag/synchronous tools (lustre-v6, lutin, rdbg).")
  )

lutils.opam

@@ -14,6 +14,7 @@ depends: [
   "base-unix"
   "ocamlfind"
   "num"
+  "camlp-streams"
 ]
 build: [
   ["dune" "build" "-p" name "-j" jobs]