Motivation for this change

Only pull patches for fixing specific functionalities in OpenCV 3 iff

1. The end user requires it in order for the functionality requested to work properly
2. The source code MUST be amended to work as intended

This also implies a specific context for each patch applied; for example, the CUDA patches are wrapped in a lib.optionals enableCUDA if-block, which tells the reader that the patches are meant for CUDA.

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.