The `Fingerprint` type is not exported from any "public"
module. It therefore seems quite strange that `Type.Reflection`
exports functions for extracting fingerprints. Remove those
exports. If fingerprints are eventually considered public,
this can be reconsidered.

Reviewers: austin, hvr, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3643