update to latest version of dampening patch

- update code to the latest version of the dampening patch:
http://altlasten.lutz.donnerhacke.de/mitarb/lutz/bind-9.9.2-dampening.patch
- description of code changes here:
http://lutz.donnerhacke.de/eng/Blog/DNS-Dampening-under-the-microscope
- Include complete Makefile instead of a patch
- Update README