Bug: Dropped comment in some cinaps code.

**Describe the bug**
The following test causes ocamlformat to exit with code 1, and an error about a comment being changed:

```
(*$
  let _ =
    [ x (*
      *)
    ; y
    ]
  ;;
*)
```

ocamlformat version: 181da779ad5cb6a19014b3c26cf13a0d244e9e4f (ocaml-ppx/main as of post creation)
command: `dune exec bin/ocamlformat/main.exe -- example.ml`
