Generate pkg-config info on Windows

[auscompgeek]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)

I am attempting to build a Python package (robotpy-cscore) that uses OpenCV as a library on Windows. We use pkgconfig to find OpenCV, for OpenCV 4 compatibility.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[hmaarrfk]

Thanks. Do you want to add a test to ensure that it is installed in the right location?

[auscompgeek]

Sounds like a good idea. I've added a test command in what is hopefully a reasonable spot.

[auscompgeek]

Well, it's a good thing I added that test. Hmm.

Upon closer inspection, it looks like OpenCV don't generate pkg-config info when building with MSVC:

https://github.com/opencv/opencv/blob/005508a07b42170e6a8d5f2ffba9aa5a1695054d/cmake/OpenCVGenPkgconfig.cmake#L1-L2

I wonder how one is supposed to discover include dirs on Windows then.

[auscompgeek]

I guess I'll close this for now, since this doesn't actually do anything useful.