experimental-reals: Superficial dependency on "analysis". #2145

Currently, the experimental-reals package depends on the analysis package, but this dependency is only superficial. experimental-reals depends only on the classical and reals packages, so its listed dependencies can be changed accordingly.

As far as I can tell, the change in dependencies requires no code change, so this update could be backported to old versions in opam and in nixpkgs. I have tested the change in nixpkgs here: MarkusKL/nixpkgs#1
I suppose that this might break existing developments that actually depend on both experimental-reals and analysis, but only has experimental-reals listed as a direct dependency.

I found this while looking into the dependencies of SSProve. Likewise, SSProve only superficially depends on analysis, but dropping the dependency will have no consequence until a change is made to experimental-reals. Dropping analysis as a direct dependency would mean faster compile times for SSProve including dependencies, especially in opam.

I would like to know if you think that this update should be applied and to what extend the changes should be backported. I will be happy to help create the pull-requests.