gitit: fix build with plugin support

Since it incurs a GHC reference anyways, we have to disable
justStaticExecutables!

pkgs/applications/misc/gitit/default.nix

@@ -1,4 +1,4 @@
-{ lib, haskellPackages, haskell, removeReferencesTo
+{ lib, haskellPackages, haskell
 # “Plugins” are a fancy way of saying gitit will invoke
 # GHC at *runtime*, which in turn makes it pull GHC
 # into its runtime closure. Only enable if you really need
@@ -7,16 +7,18 @@
 , pluginSupport ? false
 }:
 
-# this is similar to what we do with the pandoc executable
-
 let
-  plain = haskellPackages.gitit;
-  plugins =
-    if pluginSupport
-    then plain
-    else haskell.lib.compose.disableCabalFlag "plugins" plain;
-  static = haskell.lib.compose.justStaticExecutables plugins;
+  inherit (haskell.lib.compose)
+    enableCabalFlag
+    disableCabalFlag
+    justStaticExecutables
+  ;
 
+  base = (if pluginSupport then enableCabalFlag else disableCabalFlag)
+    "plugins"
+    haskellPackages.gitit;
 in
 
-static
+if pluginSupport
+then base
+else justStaticExecutables base