macOS crash in imshow with Qt5.15 #376

See opencv/opencv#18079 for background.

I do not own a Mac so I cannot fix this easily by myself without trial and error which will take a lot of time. As a summary, Info.plist file should exist in the packages.

Similar issue in PyQt (note that their package structure is different): https://riverbankcomputing.com/pipermail/pyqt/2020-January/042419.html

Related things in this repository:

• Some Qt related stuff is already copied during the build process to the packages: https://github.com/skvark/opencv-python/blob/master/patches/patchQtPlugins
• Some Qt related environment variables are set during import https://github.com/skvark/opencv-python/blob/master/cv2/__init__.py