config: CMAKE_ARGS already supported by scikit-build

[henryiii]

The setup.py in OpenCV-Python manually checks for CMAKE_ARGS, and places that in the cmake_args= setup keyword. Scikit-build itself does this, and also does some post-processing on CMAKE_ARGS that is missing here, including stripping CMAKE_INSTALL_PREFIX, which cannot be set by projects. The recent (a few hours ago) 0.17.0 release of scikit-build now produces an error if it detects CMAKE_INSTALL_PREFIX in cmake_args= (since it should not be passed in), but it ignores CMAKE_ARGS (since that get set lots of places like Conda).

The ideal fix would be to require scikit-build 0.14+, another fix would be to duplicate the filtering code in scikit-build: https://github.com/scikit-build/scikit-build/blob/6df6d571ba5c7be03729dd6b4d5e543c8aaae781/skbuild/setuptools_wrap.py#L545.

Seen in pyodide/pyodide#3753. That was easy to fix, but it's likely going to hit (at least) conda builds.

Issue submission checklist

• This is not a generic OpenCV usage question (looking for help for coding, other usage questions, homework etc.)
• I have read the README of this repository and understand that this repository provides only an automated build toolchain for OpenCV Python packages (there is no actual OpenCV code here)
• The issue is related to the build scripts in this repository, to the pre-built binaries or is a feature request (such as "please enable this additional dependency")
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