When compiling without OpenCL, some classes from its namespace are still used in code.

Conflicts:
	modules/imgproc/src/opencl/integral_sqrsum.cl
	modules/nonfree/doc/feature_detection.rst
	modules/nonfree/include/opencv2/nonfree/ocl.hpp
	modules/nonfree/src/surf_ocl.cpp
	modules/nonfree/test/test_features2d.cpp
	modules/ocl/doc/image_processing.rst
	modules/ocl/include/opencv2/ocl/ocl.hpp
	modules/ocl/perf/perf_imgproc.cpp
	modules/ocl/perf/perf_match_template.cpp
	modules/ocl/src/haar.cpp
	modules/ocl/src/imgproc.cpp
	modules/ocl/src/match_template.cpp
	modules/ocl/src/opencl/haarobjectdetect.cl
	modules/ocl/src/opencl/haarobjectdetect_scaled2.cl
	modules/ocl/test/test_imgproc.cpp

This reverts commit 3dcddad8.

Conflicts:
	modules/ocl/src/opencl/haarobjectdetect.cl

This reverts commit 54ea5bba, reversing
changes made to 28e0d3d7.