specialiser loop with cyclic superclass dictionaries
This is a regression in 9.14.1, also affecting 9.14.2
```hs
{-# LANGUAGE UndecidableInstances, UndecidableSuperClasses, FlexibleInstances #-}
module Callee where
class D2 a => D1 a
class D1 a => D2 a
instance D2 Int => D1 Int
instance D1 Int => D2 Int
{-# NOINLINE b #-}
b :: D1 a => a -> Int
b _ = 42
```
```hs
module Main where
import Callee
main = print (b (3 :: Int))
```
```bash
$ ghc -O2 -fexpose-all-unfoldings -c Callee.hs
$ ghc -O2 -c Main.hs
stack overflow: use +RTS -K<size> to increase it
```
issue