implement fix for Ormolu in nix-shell

[peterbecich]

Closes #1337

Implemented this suggestion: #1337 (comment)

It is tested here: https://github.com/peterbecich/haskell.nix-ghcjs-issue/tree/test-ormolu
nix-shell works; ormolu is available

[nix-shell:~/haskell/haskell.nix-ghcjs-issue]$ ormolu --version
ormolu 0.5.0.0 UNKNOWN UNKNOWN
using ghc-lib-parser 9.2.2.20220307

[nix-shell:~/haskell/haskell.nix-ghcjs-issue]$ which ormolu
/nix/store/61zk1g60k5m0lq8nxw3i4dhqyafar954-ormolu-exe-ormolu-0.5.0.0/bin/ormolu

[michaelpj]

Please include comments for things like this so we know when we can remove them!