[sledge] Add Containers.Ord

Reviewed By: da319

Differential Revision: D24746233

fbshipit-source-id: 5160decb3

sledge/nonstdlib/NS.mli

@@ -43,6 +43,8 @@ module Poly : sig
   val hash : 'a -> int
 end
 
+module Ord = Containers.Ord
+
 (** Function combinators *)
 
 val ( let@ ) : ('a -> 'b) -> 'a -> 'b

sledge/nonstdlib/NS0.ml

@@ -55,6 +55,8 @@ module Poly = struct
   let hash = Stdlib.Hashtbl.hash
 end
 
+module Ord = Containers.Ord
+
 (** Function combinators *)
 
 let ( >> ) f g x = g (f x)