hackage2nix: do not generate an expression for acme-everything

The package expression for acme-everything is huge since it has to
list all packages released to Hackage as of 2018 twice. As this package
isn't actually useful and probably doesn't even have a valid install
plan, we can remove it to keep the size of hackage-packages.nix in
check.

In the future, such exclusions should be decided by configurable
exclusions as proposed in #667.
It may be a prudent idea to use the spam and acme categories of Hackage
as a baseline for package exclusions.

This partially reverts commit d105bfc.

Author: sternenseemann

cabal2nix/hackage2nix/Main.hs

@@ -81,7 +81,8 @@ main = do
   config <- sconcat <$> mapM (\file -> readConfiguration (nixpkgsRepository </> file)) configFiles
   nixpkgs <- readNixpkgPackageMap nixpkgsRepository (Just "{ config = { allowAliases = false; }; }")
   preferredVersions <- readPreferredVersions (fromMaybe (hackageRepository </> "preferred-versions") preferredVersionsFile)
-  let fixup = over (at "hermes") (fmap (set (contains "1.3.4.3") False))  -- TODO: https://github.com/haskell/hackage-server/issues/436
+  let fixup = Map.delete "acme-everything" -- TODO(@wolfgangwalther): remove after https://github.com/NixOS/cabal2nix/pull/667
+              . over (at "hermes") (fmap (set (contains "1.3.4.3") False))  -- TODO: https://github.com/haskell/hackage-server/issues/436
   hackage <- fixup <$> readHackage hackageRepository
   let
       hackagePackagesFile :: FilePath