haskell.compiler.ghc884: remove big-parallel
haskell.compiler.ghc884: remove big-parallel

GHC 8.8.4 seems to be quite susceptible to flaky build failures when
using more cores. Since we don't care about speed too much with this
one, let's disable big-parallel again.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs