* Introduces error throw for line drawn with THICKNESS=0

it fuse ocl kernels to reduce kernel enqueue
Signed-off-by: Li Peng <peng.li@intel.com>

Signed-off-by: Li Peng <peng.li@intel.com>

Signed-off-by: Li Peng <peng.li@intel.com>

- specify PKG_CONFIG_LIBDIR environment variable to new target SYSROOT

* Add a 512 bit codepath to the AVX512 fastConv function

this patch adds a 512 wide codepath to the fastConv() function for
AVX512 use.
The basic idea is to process the first N * 16 elements of the vector
with avx512, and then run the rest of the vector using the traditional
AVX2 codepath.

* dnn: use unaligned AVX512 load (OpenCV aligns data on 32-byte boundary)

* dnn: change "vecsize" condition for AVX512

* dnn: fix indentation

- CMAKE_FIND_ROOT_PATH_MODE_PROGRAM: ONLY => NEVER
- update handling of CMAKE_FIND_ROOT_PATH_MODE_* variables

Signed-off-by: Li Peng <peng.li@intel.com>

Fix cv::CommandLineParser::check() documentation

- moved to table title
- can be restored via '--show_units' option
- fix microseconds: mks -> us

* Use Intel TBB's task arena if possible

 calib3d: add stereoCalibrateExtended (#10667)

* cvCalibrateCamera2Internal: simplify per view error computation

* calib3d: add stereoCalibrateExtended

- allow CALIB_USE_EXTRINSIC_GUESS
- returns per view errors

* calib3d: add stereoCalibrateExtended test

* cmake: enable CPU dispatching for AVX512 (SKX)

* cmake: update handling of unsupported flags/modes

OpenCV pthreads-based implementation changes:
- rework worker threads pool, allow to execute job by the main thread too
- rework synchronization scheme (wait for job completion, threads 'pong' answer is not required)
- allow "active wait" (spin) by worker threads and by the main thread
- use _mm_pause() during active wait (support for Hyper-Threading technology)
- use sched_yield() to avoid preemption of still working other workers
- don't use getTickCount()
- optional builtin thread pool profiler (disabled by compilation flag)