[sledge] Interpret conversions between pointer types as identity

Summary:
Since non-integral address spaces are not currently supported anyhow,
this does not introduce additional infidelity.

Reviewed By: da319

Differential Revision: D24746234

fbshipit-source-id: 1f6887a78

sledge/src/llair_to_Fol.ml

@@ -86,6 +86,7 @@ and term : Llair.Exp.t -> T.t =
         | Some fml -> F.inject fml
         | _ -> uap1 (Unsigned bits) a
       else uap1 (Unsigned bits) a
+  | Ap1 (Convert {src= Pointer _}, Pointer _, e) -> term e
   | Ap1 (Convert {src}, dst, e) ->
       let s =
         Format.asprintf "convert_%a_of_%a" Llair.Typ.pp dst Llair.Typ.pp src