kdePackages.kapidox: mark broken

It doesn't actually do anything and was only working because of the hook.

pkgs/kde/frameworks/kapidox/default.nix

···
 { mkKdeDerivation }:
 mkKdeDerivation {
   pname = "kapidox";
+
+  # doesn't actually install anything - good thing it's unused
+  meta.broken = true;
 }