Merge remote-tracking branch 'origin/2.4' into merge-2.4

Merge remote-tracking branch 'origin/2.4' into merge-2.4

Conflicts:
	modules/imgproc/src/opencl/precornerdetect.cl
	modules/nonfree/perf/perf_main.cpp
	modules/nonfree/perf/perf_surf.ocl.cpp
	modules/ocl/src/arithm.cpp
	modules/ocl/src/gftt.cpp
	modules/ocl/src/opencl/arithm_bitwise.cl
	modules/ocl/src/opencl/arithm_bitwise_binary_scalar_mask.cl
	modules/ocl/src/opencl/arithm_minMax.cl
	modules/ocl/src/opencl/arithm_nonzero.cl
	modules/ocl/src/opencl/arithm_sum.cl
	modules/ocl/test/test_arithm.cpp
	modules/viz/src/precomp.hpp
	modules/viz/src/vizcore.cpp
	modules/viz/src/vtk/vtkCloudMatSink.h
	modules/viz/src/vtk/vtkXYZReader.cpp
	modules/viz/src/vtk/vtkXYZReader.h
	modules/viz/test/test_precomp.hpp