This is a better way to accomplish the box-blur cl operation by using ocl's
local memory from the opencv source code. It use the local shared memory to
reduce global memory access, which significantly reduces the kernel's processing
time by 70 percent compared to the original one. Because of the barriers and
local worksize limitation, processing with a radius larger than 110 becomes
slower than original algorithm, so I keep the original kernels in order to deal
with box-blur with radius larger than 110.
All the tests are based on Intel Beginet and Intel IvyBridge CPU and GPU.

v2:add kernel attribute to restrict the local size to (256,1,1).

Signed-off-by: Yongjia Zhang<yongjia.zhang@intel.com>