OpenCL runtime does not require OpenCL development file (libOpenCL.so),
just the "run" library (so.1).

This patch searches for the run library (so.1) if the dev library (.so)
is not found.

Web search shows that this error has been present since at least 2015
http://answers.opencv.org/question/80532/haveopencl-return-false/Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>

It should handle bool value not only of "true" but also of "TRUE" and "True".

Fix doxygen comment in BFMatcher

numpy 1.13.0+

- '-fvisibility' flag was updated
- PVAPI library detection was changed

Fixing explicitly call download method for cuda::GpuMat object

[GSOC] Enable OCL for AKAZE (#9330)

* revert e0489cb4 - reenable OCL for AKAZE

* deal with conversion internally in AKAZE

* pass InputArray directly to AKAZE to allow distiguishing input Mat/UMat. deal with conversion there
* ensure that keypoints orientations are always computed. prevents misuse of internal AKAZE class.

* covert internal AKAZE functions to use InputArray/OutputArray

* make internal functions private in AKAZE

* split OCL and CPU paths in AKAZE

* create 2 separate pyramids, 1 for OCL and 1 for CPU
* template functions that use temporaries to always store them as correct type (UMat/Mat)

* remove variable used only in OCL path

causes unused variable warning

* update AKAZE documentation

* run ocl version only when ocl is enabled

* add tests for OCL path in AKAZE

* relax condition for keypoints angle