- control using of clEnqueueMapBuffer or clEnqueueReadBuffer[Rect]
- added benchmarks with OpenCL buffer access use cases

backporting commit 99436bb8

backporting commit 673eb2b0

* 3rdparty: update libwebp 1.0.3 => 1.1.0

- https://github.com/webmproject/libwebp/releases/tag/v1.1.0

* 3rdparty(libwebp): re-apply OpenCV patches