4.x
Merge remote-tracking branch 'upstream/3.4' into merge-3.4
Merge pull request #15959 from mshabunin:refactor-ml-tests
Merge pull request #18061 from danielenricocahall:fix-kd-tree
ml: use OpenCV license header for logistic regression
Merge pull request #11897 from Jakub-Golinowski:hpx_backend
Merge pull request #23109 from seanm:misc-warnings
fix legacy constants
Merge pull request #19884 from danielenricocahall:fix-prediction-features-bug