Also cv::, cv::gpu:: and cv::ocl:: namespace prefixes can be safely omitted
inside CV_ENUM and CV_FLAGS

It is already marked as a gtest 1.7.0

Merge branch '2.4_ocl_bfmatcher_newtype' of https://github.com/pengx17/opencv into 2.4_ocl_bfmatcher_newtype

RadiusMatch for HammingDist cannot pass yet.

This protects from unwanted implicit conversions between types at compile time.