rts: remove unused functions, fix validate on OS X

After a toolchain update, Clang is no longer appreciative of the fact
these are unused, thanks to -Werror during validate.

Signed-off-by: Austin Seipp <austin@well-typed.com>
(cherry picked from commit 7ef3f0d6dbd54d9e58fb6ab1f2db322bc8fac37a)
Temporarily fight off build bogons on OS X

Right now there's a bug with Clang that prevents 'cabal haddock' from
working nicely. But there's an easy fix for now.

Signed-off-by: Austin Seipp <austin@well-typed.com>
(cherry picked from commit 52c6dc970272437aa83a936fc1fe63977fa6178d)