WIP: DLS debugging, remove an extra call to [caml_dls_dget]

The call was placed here for thread-safety, to work correctly if
another thread (on the same domain) resizes the DLS array under our
feet. It is also the only notable change in terms of access to
`Caml_state->dls_root` since 5.1, so it might be involved in the
mysterious crash being investigated at

  ocaml-multicore/multicoretests#446

stdlib/domain.ml

@@ -163,16 +163,6 @@ module DLS = struct
     else begin
       let v : a = init () in
       let new_obj = Obj_opt.some (Sys.opaque_identity v) in
-      (* At this point, [st] or [st.(idx)] may have been changed
-         by another thread on the same domain.
-
-         If [st] changed, it was resized into a larger value,
-         we can just reuse the new value.
-
-         If [st.(idx)] changed, we drop the current value to avoid
-         letting other threads observe a 'revert' that forgets
-         previous modifications. *)
-      let st = get_dls_state () in
       if array_compare_and_set st idx obj new_obj
       then v
       else begin