lofs: use lstat rather than stat to generate qids

This copes better with the case where the symlink is dangling. The
generated qid will refer to the symlink rather than the linked file.

Signed-off-by: David Scott <dave.scott@unikernel.com>

unix/lofs9p.ml

@@ -29,7 +29,7 @@ let errors_to_client = function
 
 (* We need to associate files with Qids with unique ids and versions *)
 let qid_of_path realpath =
-  Lwt_unix.LargeFile.stat realpath
+  Lwt_unix.LargeFile.lstat realpath
   >>= fun stats ->
   let open Types.Qid in
   let flags =