opam-lint should warn if the ocaml constraint doesnt match analysis

[avsm]

The analysis phase solves for the versions of OCaml that have a valid solution.

In the opam-lint check, we should also check that the ocaml constraint matches the package set found by analysis. It's often out of sync as dependencies evolve.

[talex5]

Often you want it to be out-of-sync, though. e.g. if I depend on libfoo and it doesn't support a new OCaml compiler that just came out then I don't want to have to add a constraint to my project. I just want to wait until libfoo is fixed.

[novemberkilo]

Visiting this as part of a general cleanup.

@avsm is this still an issue? @talex5 makes a good point - perhaps there is additional context that we're missing? Thanks.