Fix the static build (#1534)

* openssl linking fix is required after all

* remove Cabal override (obsoleted on new nixpkgs)

nix/overlays/default.nix

@@ -0,0 +1,6 @@
+{
+  gitignore = import ./gitignore.nix;
+  haskell-packages = import ./haskell-packages;
+  postgresql-default = import ./postgresql-default.nix;
+  postgresql-legacy = import ./postgresql-legacy.nix;
+}

nix/overlays/haskell-packages/Cabal.nix

@@ -1,90 +0,0 @@
-{ mkDerivation
-, array
-, base
-, base-compat
-, base-orphans
-, binary
-, bytestring
-, containers
-, deepseq
-, Diff
-, directory
-, filepath
-, integer-logarithms
-, mtl
-, optparse-applicative
-, parsec
-, pretty
-, process
-, QuickCheck
-, stdenv
-, stm
-, tagged
-, tar
-, tasty
-, tasty-golden
-, tasty-hunit
-, tasty-quickcheck
-, temporary
-, text
-, time
-, transformers
-, tree-diff
-, unix
-}:
-mkDerivation {
-  pname = "Cabal";
-  version = "3.0.0.0";
-  sha256 = "5143ec26d740c1a508c93a8860e64407e7546c29b9817db20ff1595c1968d287";
-  setupHaskellDepends = [ mtl parsec ];
-  libraryHaskellDepends = [
-    array
-    base
-    binary
-    bytestring
-    containers
-    deepseq
-    directory
-    filepath
-    mtl
-    parsec
-    pretty
-    process
-    text
-    time
-    transformers
-    unix
-  ];
-  testHaskellDepends = [
-    array
-    base
-    base-compat
-    base-orphans
-    binary
-    bytestring
-    containers
-    deepseq
-    Diff
-    directory
-    filepath
-    integer-logarithms
-    optparse-applicative
-    pretty
-    process
-    QuickCheck
-    stm
-    tagged
-    tar
-    tasty
-    tasty-golden
-    tasty-hunit
-    tasty-quickcheck
-    temporary
-    text
-    tree-diff
-  ];
-  doCheck = false;
-  homepage = "http://www.haskell.org/cabal/";
-  description = "A framework for packaging Haskell software";
-  license = stdenv.lib.licenses.bsd3;
-}

nix/overlays/haskell-packages/default.nix

@@ -1,10 +1,7 @@
-{ compiler, static ? false }:
+{ compiler, extraOverrides ? (final: prev: { }) }:
 
 self: super:
 let
-  lib =
-    self.haskell.lib;
-
   overrides =
     final: prev:
     rec {
@@ -15,16 +12,7 @@ let
             ver = "0.3.0";
             sha256 = "0iwh4wsjhb7pms88lw1afhdal9f86nrrkkvv65f9wxbd1b159n72";
           } { };
-
-      cabal2nix =
-        if static then
-        # cabal2nix depends on Cabal 3.0.*, while our pinned version of
-        # Nixpkgs only provides 2.4 or 3.2. So we pinned 3.0.0.0 in
-        # ./Cabal.nix
-          prev.cabal2nix.overrideScope (self: super: { Cabal = self.callPackage ./Cabal.nix { }; })
-        else
-          prev.cabal2nix;
-    };
+    } // extraOverrides final prev;
 in
 {
   haskell =