[herd] Fix placement of po edges in dot graphs

Author: fsestini

herd/Pretty.ml

@@ -827,7 +827,7 @@ module Make (S:SemExtra.S) : S with module S = S  = struct
   | E.IdSome ii ->
       fprintf chan "proc:%s poi:%i\\l"
         (Proc.pp ii.A.proc)
-        ii.A.static_poi
+        ii.A.program_order_index
 
 (*
   This complex function is not meant to be used directly,

herd/prettyUtils.ml

@@ -23,7 +23,7 @@ module Make(S : SemExtra.S) = struct
     let by_po =
       E.EventSet.fold
         (fun e k ->
-          match E.static_poi e with
+          match E.progorder_of e with
             | None -> k
             | Some poi ->
                let es_poi = IntMap.safe_find []  poi k in