Fix building ghc964 with latest nixpkgs-unstable pin (#2333)

Fixes #2330

This fixes GHC 9.6.4 native, musl and ghcjs.  For mingwW64 and arm cross compilation it looks we still need to build a more recent GHC version (see https://ci.zw3rk.com/eval/46036#tabs-still-fail).

Author: hamishmack

overlays/bootstrap.nix

@@ -684,12 +684,7 @@ in {
                 bootPkgs = bootPkgsGhc94 // {
                   ghc = if final.stdenv.buildPlatform != final.stdenv.targetPlatform
                     then final.buildPackages.buildPackages.haskell-nix.compiler.ghc961
-                    else final.buildPackages.buildPackages.haskell.compiler.ghc966
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc965
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc964
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc963
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc962
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc945
+                    else final.buildPackages.buildPackages.haskell.compiler.ghc945
                           or final.buildPackages.buildPackages.haskell.compiler.ghc944
                           or final.buildPackages.buildPackages.haskell.compiler.ghc943;
                 };
@@ -710,11 +705,7 @@ in {
                 bootPkgs = bootPkgsGhc94 // {
                   ghc = if final.stdenv.buildPlatform != final.stdenv.targetPlatform
                     then final.buildPackages.buildPackages.haskell-nix.compiler.ghc962
-                    else final.buildPackages.buildPackages.haskell.compiler.ghc966
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc965
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc964
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc963
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc962
+                    else final.buildPackages.buildPackages.haskell.compiler.ghc962
                           or final.buildPackages.buildPackages.haskell.compiler.ghc945
                           or final.buildPackages.buildPackages.haskell.compiler.ghc944
                           or final.buildPackages.buildPackages.haskell.compiler.ghc943;
@@ -736,10 +727,7 @@ in {
                 bootPkgs = bootPkgsGhc94 // {
                   ghc = if final.stdenv.buildPlatform != final.stdenv.targetPlatform
                     then final.buildPackages.buildPackages.haskell-nix.compiler.ghc963
-                    else final.buildPackages.buildPackages.haskell.compiler.ghc966
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc965
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc964
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc963
+                    else final.buildPackages.buildPackages.haskell.compiler.ghc963
                           or final.buildPackages.buildPackages.haskell.compiler.ghc962
                           or final.buildPackages.buildPackages.haskell.compiler.ghc945
                           or final.buildPackages.buildPackages.haskell.compiler.ghc944
@@ -762,9 +750,7 @@ in {
                 bootPkgs = bootPkgsGhc94 // {
                   ghc = if final.stdenv.buildPlatform != final.stdenv.targetPlatform
                     then final.buildPackages.buildPackages.haskell-nix.compiler.ghc964
-                    else final.buildPackages.buildPackages.haskell.compiler.ghc966
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc965
-                          or final.buildPackages.buildPackages.haskell.compiler.ghc964
+                    else final.buildPackages.buildPackages.haskell.compiler.ghc964
                           or final.buildPackages.buildPackages.haskell.compiler.ghc963
                           or final.buildPackages.buildPackages.haskell.compiler.ghc962
                           or final.buildPackages.buildPackages.haskell.compiler.ghc945