haskellPackages.xmonad: drop upstreamed Nix compat patch

We had a long standing downstream patch for XMonad allowing us to
override the ghc and xmessage binaries used. That has been upstreamed
and released in 0.17.1 and we can drop it!

* patch upstreamed in https://github.com/xmonad/xmonad/pull/409
* downstream patch adjusted in https://github.com/NixOS/nixpkgs/pull/184784

pkgs/development/haskell-modules/configuration-nix.nix

@@ -230,9 +230,6 @@ self: super: builtins.intersectAttrs super {
     preConfigure = "export TZDIR=${pkgs.tzdata}/share/zoneinfo";
   }) super.tz;
 
-  # Nix-specific workaround
-  xmonad = appendPatch ./patches/xmonad_0_17_0-nix.patch (dontCheck super.xmonad);
-
   # https://hydra.nixos.org/build/128665302/nixlog/3
   # Disable tests because they require a running dbus session
   xmonad-dbus = dontCheck super.xmonad-dbus;

pkgs/development/haskell-modules/patches/xmonad_0_17_0-nix.patch

@@ -1,34 +0,0 @@
-diff --git a/src/XMonad/Core.hs b/src/XMonad/Core.hs
-index 46a0939..92af53d 100644
---- a/src/XMonad/Core.hs
-+++ b/src/XMonad/Core.hs
-@@ -46,6 +46,7 @@ import Data.Traversable (for)
- import Data.Time.Clock (UTCTime)
- import Data.Default.Class
- import Data.List (isInfixOf)
-+import System.Environment (lookupEnv)
- import System.FilePath
- import System.IO
- import System.Info
-@@ -458,7 +459,8 @@ xfork x = io . forkProcess . finally nullStdin $ do
- -- | Use @xmessage@ to show information to the user.
- xmessage :: MonadIO m => String -> m ()
- xmessage msg = void . xfork $ do
--    executeFile "xmessage" True
-+    xmessageBin <- fromMaybe "xmessage" <$> liftIO (lookupEnv "XMONAD_XMESSAGE")
-+    executeFile xmessageBin True
-         [ "-default", "okay"
-         , "-xrm", "*international:true"
-         , "-xrm", "*fontSet:-*-fixed-medium-r-normal-*-18-*-*-*-*-*-*-*,-*-fixed-*-*-*-*-18-*-*-*-*-*-*-*,-*-*-*-*-*-*-18-*-*-*-*-*-*-*"
-@@ -654,8 +656,9 @@ compile dirs method =
-         bracket (openFile (errFileName dirs) WriteMode) hClose $ \err -> do
-             let run = runProc (cfgDir dirs) err
-             case method of
--                CompileGhc ->
--                    run "ghc" ghcArgs
-+                CompileGhc -> do
-+                    ghc <- fromMaybe "ghc" <$> (lookupEnv "XMONAD_GHC")
-+                    run ghc ghcArgs
-                 CompileStackGhc stackYaml ->
-                     run "stack" ["build", "--silent", "--stack-yaml", stackYaml] .&&.
-                     run "stack" ("ghc" : "--stack-yaml" : stackYaml : "--" : ghcArgs)