Add progpow-debug.diff, which outputs digest for a fixed header and nonce

[solardiz]

Having a patch like this in the tree should be better than not having any testing/debugging capabilities at all, although ideally ProgPoW would have this functionality without a need to patch.

[ifdefelse]

Instead of checking in a .diff, can you wrap these changes in a #ifdef?

[solardiz]

I can. Please suggest what to call the macro enabling this debugging mode, and how/where we'd recommend people to set it (when needed).

[solardiz]

Thinking of this some more, it's a bit complicated: some of the changes are in kernels, so we'd need to pass the macro to kernel builds. I think it's better to check in the .diff for now.