opencv: use c++ 17 to fix protobuf support

[ZeroEcks]

At some point protobuf was disabled due to not using C++ 17. This commit enables it just like what they had to do over in brew.. This fixes #386327

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[ZeroEcks]

Tests pass on linux, same issue as on OfBorg on darwin. It seems unrelated to my changes however, I think the tests are just broken on darwin.

[SuperSandro2000]

Has that similar implications as abseilcpp that we need multiple versions with multiple c++ versions?

[SuperSandro2000]

As an alternative I would take a look at #375774

[ZeroEcks]

@SuperSando2000 can you clarify the implications in abseilcpp or link the issue for me?

[eclairevoyant]

As an alternative I would take a look at #375774

That other PR downgrades protobuf as used by opencv in the second commit (623bb414eed06f91e85792189c800453f8c34557), is that the best solution here?

[eclairevoyant]

@ZeroEcks Please rebase, do not use merging in nixpkgs. The merge commit needs to be dropped in this case.

[ZeroEcks]

changes have been implemented in the other PR, I think this is not needed anymore :)