opencv: Add a override option to enable V4L2 support

[Sigmanificient]

Issue description

I would like to compile a software that uses opencv with the V4L2 module, but currently facing a compile error:

src/camera/new_camera.cpp: In function 't_bunny_camera* bunny_new_camera(int)':
src/camera/new_camera.cpp:18:42: error: 'CAP_V4L2' is not a member of 'cv'
   18 |       cam = new cv::VideoCapture(id, cv::CAP_V4L2);
      |                                     

Additional context

I didn't find any override option to enable it, but on stack overflow, I found a post about it which suggest to add the following cmake flags:

-DWITH_V4L=ON 
-DWITH_LIBV4L=ON

However I couldn't get it to work.

Notify maintainers

@basvandijk

Metadata

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
 - system: `"x86_64-linux"`
 - host os: `Linux 6.6.30, NixOS, 24.05 (Uakari), 24.05.20240511.062ca2a`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.18.2`
 - channels(root): `"nixos-23.05"`
 - channels(sigmanificient): `""`
 - nixpkgs: `/nix/store/pfc56yr7y3wflvbgnrpscf2n1m4j3xd7-source`