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.

Update system.cpp

Update system.cpp

Update ocl.cpp

Update matching.cpp

Update ocl.cpp

Update matching.cpp

generalized OpenCL version of cv::sepFilter2D; removed some restrictions and added 3-channels support