dee: disable unused-result error

pkgs/development/libraries/dee/default.nix

@@ -56,6 +56,10 @@ stdenv.mkDerivation rec {
     "--with-pygi-overrides-dir=${placeholder "py"}/${python3.sitePackages}/gi/overrides"
   ];
 
+  # Compilation fails after a change in glib where
+  # g_string_free now returns a value
+  env.NIX_CFLAGS_COMPILE = "-Wno-error=unused-result";
+
   enableParallelBuilding = true;
 
   meta = with lib; {