ethminer: provide a CUDA-free version

[Atemu]

Motivation for this change

The cuda version is broken and my AMDGPU system doesn't need it to be built with CUDA.

cc @nand0p @noneucat @r-burns @danieldk

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[r-rmcgibbo]

Result of nixpkgs-review pr 120588 at 12675a7 run on x86_64-linux 1

2 packages marked as broken and skipped:

• ethminer
• ethminer-cuda

1 package built successfully:

• ethminer-free

1 suggestion:

• warning: unclear-gpl

  gpl2 is a deprecated license, please check if project uses gpl2Plus or gpl2Only and change meta.license accordingly.

  Near pkgs/tools/misc/ethminer/default.nix:83:5:

     |
  83 |     license = licenses.gpl2;
     |     ^
  

[SuperSandro2000]

Suggested change

	{
	lib,
	stdenv,
	clangStdenv,
	fetchFromGitHub,
	{ lib
	, stdenv
	, clangStdenv
	, fetchFromGitHub

Please format the inputs in this style.

[Atemu]

Could we leave style nitpickings on portions I didn't even really touch out of this? Thanks.

If you want to "fix" code style (we don't even have a style guide) feel free to make PRs specific to that purpose (I'd genuinely like that!) but please don't ask me to do that for you in PRs which are not.
I get it, style is important. I try to "fix" sections which I perceive as not conforming to the "norms" when there's a good opportunity (i.e. I'm reworking it in large parts anyways) but you cannot expect people to go out of their way to do that sort of thing where it wouldn't be necessary.

I didn't open ethminer's default.nix and said to myself "Boy golly, I'm going to fix this file's styling!", I opened it to make a functional change with actual value to users.

As a contributor, I see such reviews as entirely unnecessary and even discouraging.

[danieldk]

It's nice to have have derivations buildable without CUDA support as well. LGTM. I added one small suggestion to use cudaSupport, since it is more standardized in nixpkgs.

[danieldk]

@ofborg build ethminer ethminer-cuda ethminer-free