HERMIT users depend on RULES to specify equational properties. 6.10.2
performed both inlining and simplification in both sides of the rules,
meaning they can't really be used for this. This breaks most HERMIT use
cases.  A separate commit already disabled this for the LHS of rules.
This does so for the RHS.

See Trac #10829 for nofib results.

Reviewed By: austin, bgamari, simonpj

Differential Revision: https://phabricator.haskell.org/D1246

GHC Trac Issues: #10829