Summary:
Although these functions were marked as CONSTANT_FOLDED, they did
not have a corresponding builtinRule in PrelRules. The idea was
probably to add them eventually, but this hasn't manifested so
far.

The plan is to eventually add builtin rules for these functions
over Natural, so as a reminder we simply comment out the
CONSTANT_FOLDED  annotation instead of removing it completely.

Reviewers: hvr, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, carter

Differential Revision: https://phabricator.haskell.org/D5267

(cherry picked from commit 3ec6fe8827956cc36b58cdf0bb1f5752eaa2a8ea)