ghc-bignum will become reinstallable (potentially with different backends) and GHC itself is backend agnostic. So don't expose bignum backend with
ghc --info (which can be wrong, cf #20495 (closed)) but expose it with
Querying the backend can now easily be done with:
❯ _build/stage1/bin/ghc -e "GHC.Num.Backend.backendName" "native"