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
put IPP ReduceSum_32f back
trying to make the tests pass
Merge pull request #3020 from vpisarev:ocl_disable_more_funcs
fixed ocl_flip for cn==3