Merge commit '43aec5ad' into merge-2.4

Conflicts:
	cmake/OpenCVConfig.cmake
	cmake/OpenCVLegacyOptions.cmake
	modules/contrib/src/retina.cpp
	modules/gpu/doc/camera_calibration_and_3d_reconstruction.rst
	modules/gpu/doc/video.rst
	modules/gpu/src/speckle_filtering.cpp
	modules/python/src2/cv2.cv.hpp
	modules/python/test/test2.py
	samples/python/watershed.py

modules/imgproc/perf/perf_cornerHarris.cpp

@@ -36,4 +36,4 @@ PERF_TEST_P(Img_BlockSize_ApertureSize_k_BorderType, cornerHarris,
     TEST_CYCLE() cornerHarris(src, dst, blockSize, apertureSize, k, borderType);
 
     SANITY_CHECK(dst, 2e-5);
-}
+}