Previusly we simply weren't doing CSE at all on things
whose unfolding were not always-active, for reasons explained
in Note [CSE for INLINE and NOINLINE].  But that was bad!
Making something INLNEABLE meant that its RHS was no longer
CSE'd, and that made some nofib programs worse.

And it's entirely unnecessary.  I thoguht it through again,
wrote new comments (under the same Note), and things are
better again.