(Just keeping track of this bug while working on #574)

On macos, the examples/fts/foreign version fails due to getting an invalid argument back for fts_info, but the stubgen one succeeds.

$ ./_build/fts.native  .
Fatal error: exception Invalid_argument("fts_info")

It seems to be a different number every time for fts_info_of_int, so needs more investigation.