* Emit warning for fixities with no export modifiers
This is to help update all the existing code to program with explicit
fixity export directives in preparation for the behavioral change where
they will become private by default.
* Don't require a runtime value of `x` for `succNotLTEpred`
* Add `succNotLTEpred` as an instance of `Uninhabited`
* Add contribution to changelog
* Update golden value for test `basic044`
