Rename ty{Con,peRep}Hash to ty{Con,peRep}Fingerprint

This is a follow-up change to 56e0ac98

See also discussion at
https://groups.google.com/d/msg/haskell-core-libraries/e9N3U6nJeQE/V-TvG3G-3x4J

(cherry picked from commit 842028b4)