Bump ghc 9.10.1 with CPP

[philderbeast]

See #564. Adds CPP conditionals.

To test for each ghc-x.y.z, when x.y.z = {9.4.8, 9.6.5, 9.8.2, 9.10.1}:

$ cabal clean
$ cabal build all --project-file=ghc-x.y.z.cabal.project
$ cabal test all --test-show-details=always --project-file=ghc-x.y.z.cabal.project

$ stack purge
$ stack test --stack-yaml=ghc-x.y.z.stack.yaml

Note

stack.yaml and cabal.project are set up for ghc-9.10.1.

[tomjaguarpaw]

Thanks! I took the CPP and incorporated it into #571

If you'd like to submit the other pieces please open a new PR. We already have a CI system that tests a range of GHC versions, so I didn't understand what the changes were for.