OpenCV 4 compatibility fix for caffe2/video (#24143)
Summary:
Trying to fix https://github.com/pytorch/pytorch/issues/24073 as in https://github.com/pytorch/pytorch/issues/9966. Make caffe2 compile with OpenCV 4.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/24143
Differential Revision: D16753624
Pulled By: ezyang
fbshipit-source-id: 524eac10a9285e0c0a803a8566917aa95aa0662c
