* remove race condition
  * upload _prevPts to OpenCL device explicitly before calling "sparse"

Fix OpenCL's wrong output of calcOpticalFlowPyrLK function's output vector of err. Improve err's precison of the calcOpticalFlowPyrLK OpenCL function and add the relative test.

It could reduce 7 multiplications every iteration.
Signed-off-by: Yan Wang <yan.wang@linux.intel.com>

1. Remove uncessary index calculation.
2. Use mad/mad24 as possible.
Signed-off-by: Yan Wang <yan.wang@linux.intel.com>

1. decrease branch number in CL code by replacing them into weights
2. decrease local mem pressure in reduce operation by using private variables
3. decrease image sampler pressure by caching data into local memory
4. remove unnecessary sync point on the HOST side.

static function qualifier replaced on inline to enable kernel compilation with OpenCL 1.1 embedded profile.

Add CL_CPU to supportsFeature check
simplify the logic of pyrlk