* loosen some test threshold mainly for integer types
  * use relative error for floating points result
  * avoid division by zero by following the comment
  * fix the indentation

Found via `codespell`

- removed tr1 usage (dropped in C++17)
- moved includes of vector/map/iostream/limits into ts.hpp
- require opencv_test + anonymous namespace (added compile check)
- fixed norm() usage (must be from cvtest::norm for checks) and other conflict functions
- added missing license headers

SPIR kernels are located in opencv_extra

https://sourceforge.net/p/predef/wiki/OperatingSystems

 * disable vector operation for now
 * brush up the implementation based on comment

Fix error in minmaxloc.cl
Change test for convertScaleAbs
Fix minMaxIdx for _src2 align
Change epsilon on the tests

Fixed buffer initialization in reduce kernel. Enabled OCL version of reduce for SUM, MAX, MIN modes.

1. disabled OpenCL acceleration for cv::multiply() (CV_32F), cv::divide (CV_32F), cv::convertScaleAbs (CV_32F) and cv::reduce (SUM, CV_32F), cv::reduce (MIN & MAX), cv::flip (3-channel case).
2. changed the number of test loops from 1 to 30 (except for cv::pow() test, which fails for yet unknown reason)
3. disabled IPP acceleration for 3-channel norms.
4. modified relativeNorm test function to handle very small values