gtkradiant: fix GCC 14 build

pkgs/by-name/gt/gtkradiant/package.nix

···
 
   enableParallelBuilding = true;
 
+  # GCC 14 makes these errors by default
+  env.NIX_CFLAGS_COMPILE = "-Wno-error=incompatible-pointer-types -Wno-error=implicit-function-declaration -Wno-error=int-conversion";
+
   desktopItems = [
     (makeDesktopItem {
       name = "gtkradiant";