removing unreachable codes in gbackend

[kai-waang]

Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
• The PR is proposed to the proper branch
• There is a reference to the original bug report and related work
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  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake

[dmatveev]

Hi @kai-waang ! Thanks for this PR. Does this code cause warnings so you decided to remove it? Could you please specify details of your platform if it causes any troubles? No objections with the PR but trying to understand the background.

[kai-waang]

Hi @kai-waang ! Thanks for this PR. Does this code cause warnings so you decided to remove it? Could you please specify details of your platform if it causes any troubles? No objections with the PR but trying to understand the background.

I think this PR is made when I was reading these codes and trying to do some cleaning. I'm sure it doesn't cause any warnings on my machine.

[dmatveev]

I believe (back in 2017) this code has been written to avoid some warnings.. But if it passes the current CI, there's no such warnings in 2023.

At least it is always possible to revert it in case of problems

Thanks for your contribution!