Add name to Vfile_kind functor

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>

src/super_context.ml

@@ -537,6 +537,7 @@ module Pkg_version = struct
   module V = Vfile_kind.Make(struct
       type t = string option
       let t = Sexp.To_sexp.(option string)
+      let name = "Pkg_version"
     end)
 
   let spec sctx (p : Package.t) =

src/vfile_kind.ml

@@ -46,6 +46,7 @@ module Make
     (T : sig
        type t
        val t : t Sexp.To_sexp.t
+       val name : string
      end)
   : S with type t = T.t =
 struct
@@ -56,7 +57,7 @@ struct
 
   module P = Utils.Persistent(struct
       type nonrec t = t
-      let name = "VFILE_KIND"
+      let name = "VFILE_KIND-" ^ T.name
       let version = 1
     end)
 

src/vfile_kind.mli

@@ -23,5 +23,6 @@ module Make
     (T : sig
        type t
        val t : t Sexp.To_sexp.t
+       val name : string
      end)
   : S with type t = T.t