Add backwards portability for OpenCL 1.1 when OpenCV executables
are compiled with OpenCL 1.2 profile support.

fixing precommit build on ubuntu-64 (now it takes OCL headers from non-default OCL SDK, but libs from default one)

This also fixes the bug where the Sphinx version gets detected as
"Sphinx vX.Y.Z" instead of "X.Y.Z" on Unix-like systems.

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.