Commits:
added new function, cv::ocl::attachContext(String& platformName, void* platformID, void* context, void* deviceID) which allow to attach externally created OpenCL context to OpenCV.
add definitions of clRetainDevice, clRetainContext funcs
removed definitions for clRetainContext, clRetainDevice
fixed build issue under Linux
fixed uninitialized vars, replace dbgassert in error handling
remove function which is not ready yet
add new function, cv::ocl::convertFromBuffer(int rows, int cols, int type, void* cl_mem_obj, UMat& dst, UMatUsageFlags usageFlags = cv::USAGE_DEFAULT) which attaches user allocated OpenCL clBuffer to UMat
uncommented clGetMemObjectInfo definition (otherwise prevent opencv build)
fixed build issue on linux and android
add step parameter to cv::ocl::convertFromBuffer func
suppress compile-time warning
added sample opencl-opencv interoperability (showcase for cv::ocl::convertFromBuffer func)
CMakeLists.txt modified to not create sample build script if OpenCL SDK not found in system
fixed build issue (apple opencl include dir and spaces in CMake file)
added call to clRetainContext for attachContext func and call to clRetainMemObject for convertFromBuffer func
uncommented clRetainMemObject definition
added comments and cleanup
add local path to cmake modules search dirs (instead of replacing)
remove REQUIRED for find_package call (sample build together with opencv). need to try standalone sample build
opencl-interop sample moved to standalone build
set minimum version requirement for sample's cmake to 3.1
put cmake_minimum_required under condition, so do not check if samples not builded
remove code dups for setSize, updateContinuityFlag, and finalizeHdr
commented out cmake_minimum_required(VERSION 3.1)
add safety check for cmake version
add convertFromImage func and update opencl-interop sample
uncommented clGetImageInfo defs
uncommented clEnqueueCopyImageToBuffer defs
fixed clEnqueueCopyImageToBuffer defs
add doxygen comments
remove doxygen @fn tag
try to restart buildbot
add doxygen comments to directx interop funcs
remove internal header, use fwd declarations in affected compile units instead

 - explicitly turning OCL off since WinRT does not support it
 - fixing macro definitions in core/ocl.cpp
Signed-off-by: Maxim Kostin <v-maxkos@microsoft.com>

- Substituted HAVE_WINRT with WINRT
- Fixed compilation issues in ocl.cpp and parallel.cpp
- Fixed compiler issue for WP8: "C2678: binary '+' : no operator found which takes a left-hand - Fixed gitignore
- Added #ifdef HAVE_OPENCL to remove compiler warnings in ocl.cpp
- Used NO_GETENV similar to '3rdparty\libjpeg\jmemmgr.c;
- Added ole32.lib for core module (for WindowsStore 8.0 builds)
- Made OpenCV_ARCH aware of ARM
Signed-off-by: Maxim Kostin <v-maxkos@microsoft.com>

disable "unwanted" messages

This reverts commit 7d91b8ef.

IPP can be switched on and off on runtime;

Optional implementation collector was added (switched off by default in CMake). Gathers data of implementation used in functions and report this info through performance TS;

TS modifications for implementations control;

sss

1. someMatrix.data -> someMatrix.prt()
2. someMatrix.data + someMatrix.step * lineIndex -> someMatrix.ptr( lineIndex )
3. (SomeType*) someMatrix.data -> someMatrix.ptr<SomeType>()
4. someMatrix.data -> !someMatrix.empty() ( or !someMatrix.data -> someMatrix.empty() ) in logical expressions

According to opencl 1.2 spec 5.4.2:
  enqueues a command to unmap a previously mapped region of a memory object.
  ...
  CL_INVALID_VALUE if mapped_ptr is not a valid pointer returned by
  clEnqueueMapBuffer, or clEnqueueMapImage for memobj.

So if the u->data is not from a clEnqueueMapBuffer call, we should not
call clEnqueueUnmapMemObject() unmap it. With this patch, the cases
./opencv_test_video --gtest_filter=OCL_Video/FarnebackOpticalFlow.Mat/*
could work well with beignet 0.9.1, Otherwise, it will get a
CL_INVALID_VALUE at the clEnqueueUnmapMemObject().
Signed-off-by: Zhigang Gong <zhigang.gong@intel.com>

modules/core/src/arithm.cpp:345:51:
error: constant expression evaluates to 4294967295 which cannot be narrowed to type 'int' [-Wc++11-narrowing]
static int CV_DECL_ALIGNED(16) v64f_absmask[] = { 0xffffffff, 0x7fffffff, 0xffffffff, 0x7fffffff };
                                                  ^~~~~~~~~~

Converted to unsigned int.  This variable is only used to initialize a bit pattern anywhy for a 128bit type.