continue fixing nonfree elements
fixed dependency of stitching module on xfeatures2d module as optional
fixed the initModule_xfeatures2d function that was called in module stitching since it is in another namespace than the standard cv one.
Disabled native_sqrt for double, since it may be not implemented and gives compilation error.
Merge pull request #3163 from StevenPuttemans:fix_nonfree_items
OCL: enable clAmdFftGetVersion
fix for cv::memopTypeToStr
Added check AmdFft version to be sure that AmdFft binaries are available
attempt to fix compilation of OpenCL cv::transpose for AMD
Merge pull request #3172 from ilya-lavrenov:tapi_transpose_amd
Merge pull request #3171 from akarsakov:amd_fft_fix
Merge branch 'master' of https://github.com/Itseez/opencv.git
Fixes for compiling with CUDA 6.5

Based on commit feb74b125d7923c0bc11054b66863e1e9f753141 from 2.4.9 branch.
samples: gpu: removed softcascade example

The example in question cannot be compiled anymore as the softcascade
module has been removed in 3858f2291d64652a82fea930ba5c598045633843.
samples: gpu: removed inclusion of non-existent opencv2/contrib/contrib.hpp header, re-introduced TickMeter class in a separate header

This patch removes inclusion of opencv2/contrib/contrib.hpp header,
which does not exist anymore due to removal of opencv_contrib module.

The samples including this header appear to be doing so in order to
use TickMeter class; therefore, the latter is now provided by tick_meter.hpp
header file, located in samples/gpu folder.
samples: gpu: performance: remove inclusion of opencv2/legacy.hpp header

The header is gone now, along with the opencv_legacy module.
samples: gpu: performance: removed FGDStatModel performance comparison test

The FGD background subtraction model was part of opencv_legacy module;
as it is gone now, it makes little sense to benchmark the GPU version,
either, so the whole test is removed.
samples: gpu: super_resolution: disable simple optical flow

The cv::superres::createOptFlow_Simple() function along with the
simple optical flow class implementation is currently commented out
in the superres module's code, so comment it out in the example as well.
samples: gpu: performance: fix include path for opencv_xfeatures2d

As opencv_xfeatures2d is part of opencv-contrib and not opencv repository,
${OpenCV_SOURCE_DIR}/modules/modules/include is not a correct include
path - use ${opencv_xfeatures2d_SOURCE_DIR}/include instead
samples: gpu: performance: BackgroundSubtractorMOG is now part of opencv_bgsegm module
samples: gpu: performance: SURF is now part of opencv_xfeatures2d
Fixing Matx ostream operator

cv::Matx could not be converted to c::Mat automatically