Fixed a clerical error in qrcode.py

also link to CUDA::cufft_static in case of BUILD_SHARED_LIBS=OFF

…ngle

supports empty kernels in cuda::SeparableLinearFilters opencv#3731

[#25408](opencv/opencv#25408)

When only 1D convolution is needed (row or column filter only), `cuda::LinearFilter` might be slower than `cuda::SeparableLinearFilter`
Using `cuda::SeparableLinearFilter` for 1D convolution can be done by using a `(1)` kernel for the ignored dimension.
By supporting empty kernels in `cuda::SeparableLinearFilter`, there is no need for that `(1)` kernel any more.
Additionaly, the inner `_buf ` used to store the intermediate convolution result can be saved when a single convolution is needed.

In "legacy" usage (row+col kernels), there is no regression in `cuda::SeparableLinearFilter` performance.
As soon as an empty kernel is used, the performance is largely increased.

Devil in the details : the "in-place" processing is supported and might need intermediate buf, but still no regression.

- [X] I agree to contribute to the project under Apache 2 License.
- [X] 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
- [X] The PR is proposed to the proper branch
- [X] There is a reference to the original bug report and related work
- [X] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [X] The feature is well documented and sample code can be built with the project CMake