Fix cyclic-ish dependencies between list and result (#2836)
Fix cyclic-ish dependencies between list and result (#2836)

Jenga complains about the following tricky dependency structure:

* `list.mli` depends on `result.mli` (due to the use of `Result.t`)
* `result.ml` depends on `list.ml` (due to the use of `List.rev`)

While this is not strictly speaking a cycle, it does confuse Jenga.
janestreet/jbuilder,dra27/jbuilder,dra27/jbuilder,dra27/jbuilder,janestreet/jbuilder,janestreet/jbuilder,dra27/jbuilder,dra27/jbuilder,dra27/jbuilder,janestreet/jbuilder,janestreet/jbuilder,janestreet/jbuilder