Create cczp.h

This should help build Security. Haven't tested extensively yet, but it seems to do mostly sensible things.

Main thing I'm concerned about is the `cczp_decl_n` macro, which is ignoring the size provided. Given that it's only used for globals as far as I can see, I think we can work around the pointer-ness, but I got sick of wrangling c. I guess if necessary we can just make it a hard cast, but I was hoping for something less hacky.