a few fixes of ocl::perf test cases
Fix ocl::pyrup kernel build on Mac.
Fix ocl::filter2D.
In current implementation, this function only works when anchor point is
in the kernel center and kernel size supported is either 3x3 or 5x5.
Adjust perf_filters, as this function only supports 3x3 kernel
fix a crash on Linux
Update ocl::surf_matcher sample.
The new sample adjust some parameters thus it should always be able to
calculate valid homography matrix when input is box.png and
box_in_scene.png.
Pure cpp surf and bfmatcher implementation is also added to show the user
its accuracy and performance.
Initialize OpenCL context at the end of getDevice call.
Added for better compatibility with the current samples/test cases.
User now will be able to initialize OpenCL context explicitly with
ocl::getDevice api.
This may be obsoleted in future releases.
Fix build error
Make AutoLock noncopyable (it would break on copying, anyway).
setting 'char' to be signed by default since some tests fail when it's wrong (e.g. native compilation on ARM Linux)
making the comment less ambigous
disabled samples with driver api
update util.hpp to fix OpenCL import on case sensitive mac FS

On a Mac with a case sensitive filesystem <OpenCL/OpenCL.h> does not exist but <OpenCL/opencl.h> does. I presume (!), but have no way to test, that on a Mac with case insensitive FS this change will make no difference.
update safe_call.hpp to fix OpenCL import on case sensitive mac FS

On a Mac with a case sensitive filesystem <OpenCL/OpenCL.h> does not exist but <OpenCL/opencl.h> does. I presume (!), but have no way to test, that on a Mac with case insensitive FS this change will make no difference.
change a test image of pyrlk
Fix a bug of gfft.
When user provided corners buffer is big enough to be copied to from
tmpCorners_, we allow the buffer to be reused other than allocate a new
cl_mem object.
use GoodFeaturesToTrackDetector_OCL
fixed gpu module build on arm platform

links with CUDA driver library only if we use video encoding/decoding
Merge pull request #945 from malcolmreynolds:master
Merge pull request #939 from pengx17:2.4_getDevice