* Resolves 6125

* Fix test code

* Delete unnecessary code

Arm: fix the test failure of OCL_Imgproc/CLAHETest.Accuracy on ODROID-XU4 (#11409)

* fix the test failure of OCL_Imgproc/CLAHETest.Accuracy on ODROID-XU4
  * avoid the race condition in the reduce

* imgproc(ocl): simplify CLAHE code

* remove unused class

OpenCV 3.4.1 for Intel Computer Vision SDK

for cv::Mat with type=16UC3 and width < 16

std::exception_ptr requires enabled C++11 mode

- remove duplicates
- restore "always on" missing entries
- fix FP16 detection on MSVC

for cv::Mat with width < 16

- fixed wrong condition (always true)
- replaced unnecessary shift operation: '>> 63' to '< 0'
- used CV_BIG_INT()/CV_BIG_UINT() macros

avoid using of templated 'operator T ()'

* Custom deep learning layers support

* Stack custom deep learning layers