grub4dos: mark broken

grub4dos is broken for a while after `binutils` update as:

  > checking whether objcopy works for absolute addresses... no
  > configure: error: GRUB requires a working absolute objcopy; upgrade your binutils

Upstream has an unfixed report in 2017. Let's mark the package broken.

pkgs/tools/misc/grub4dos/default.nix

@@ -39,5 +39,8 @@ in stdenv.mkDerivation {
     maintainers = with maintainers; [ abbradar ];
     platforms = platforms.linux;
     license = licenses.gpl2;
+    # Needs a port to modern binutils:
+    #   https://github.com/chenall/grub4dos/issues/160
+    broken = true;
   };
 }