* Added dependency verification mechanism for cmake

moved to CMakeFiles (no conflicts are expected)

  - add infrastructure support for Power9/VSX3
  - fix missing VSX flags on GCC4.9 and CLANG4(#13210, #13222)
  - fix disable VSX optimzation on GCC by using flag ENABLE_VSX
  - flag ENABLE_VSX is deprecated now, use CPU_BASELINE, CPU_DISPATCH instead
  - add VSX3 to arithmetic dispatchable flags

Configures and loads OpenCV bindings extension including 3rdparty dependencies

Based on running Python specify:
- configure PYTHON_PATH (via "sys.path")
- configure LD_LIBRARY_PATH / PATH

- drop EnableDelayedExpansion
- pause on failed commands (non-interactive mode)

- CMake install COMPONENT: "scripts"

* Updated ICV packages and IPP integration

* core(test): minMaxIdx IPP regression test

* core(ipp): workaround minMaxIdx problem

* core(ipp): workaround meanStdDev() CV_32FC3 buffer overrun

* Returned semicolon after CV_INSTRUMENT_REGION_IPP()

to detect process termination after ExitProcess() call

* cmake: don't ignore Python from PATH environment variable

- this breaks selection between 32/64-bit Python
- this breaks Anaconda/Conda environments
- it is not the CMake default behavior, expected by many projects

* cmake: add Python version check, fallback path on CMake 3.12+

* cmake: drop Python 2.6, allow version selection for Python 3.x

Avoids passing -Wall, which will enable literally every warning in
Clang. Avoids passing -ffunction-sections etc to clang-cl, which each
generate warnings.

* matlab: move to opencv_contrib

* cmake: preserve variables scope for processing modules

- use macro instead of function to avoid scope resets

When cross compiling with clang, the internal C++ headers are not found
when adding sysroot to -isystem, that is redundant anyway because it
will look for headers insider --sysroot path with same quality as it
would do with -isystem otherwise

Fixes errors like

FAILED: 3rdparty/openexr/CMakeFiles/IlmImf.dir/Iex/IexBaseExc.cpp.o
....
In file included from
TOPDIR/build/tmp/work/cortexa7t2hf-neon-vfpv4-bec-linux-musleabi/opencv/3.4.3+gitAUTOINC+b38c50b3_1f6d6f0626_bdb7bb85f3_34e4206aef_fccf7cd6a4-r0/git/3rdparty/openexr/Iex/IexBaseExc.cpp:43:
In file included from
TOPDIR/build/tmp/work/cortexa7t2hf-neon-vfpv4-bec-linux-musleabi/opencv/3.4.3+gitAUTOINC+b38c50b3_1f6d6f0626_bdb7bb85f3_34e4206aef_fccf7cd6a4-r0/git/3rdparty/openexr/Iex/IexBaseExc.h:48:
In file included from
TOPDIR/build/tmp/work/cortexa7t2hf-neon-vfpv4-bec-linux-musleabi/opencv/3.4.3+gitAUTOINC+b38c50b3_1f6d6f0626_bdb7bb85f3_34e4206aef_fccf7cd6a4-r0/recipe-sysroot/usr/lib//arm-bec-linux-musleabi/8.2.0/../../../include/c++/8.2.0/string:52:
In file included from
TOPDIR/build/tmp/work/cortexa7t2hf-neon-vfpv4-bec-linux-musleabi/opencv/3.4.3+gitAUTOINC+b38c50b3_1f6d6f0626_bdb7bb85f3_34e4206aef_fccf7cd6a4-r0/recipe-sysroot/usr/lib//arm-bec-linux-musleabi/8.2.0/../../../include/c++/8.2.0/bits/basic_string.h:6391:
In file included from
TOPDIR/build/tmp/work/cortexa7t2hf-neon-vfpv4-bec-linux-musleabi/opencv/3.4.3+gitAUTOINC+b38c50b3_1f6d6f0626_bdb7bb85f3_34e4206aef_fccf7cd6a4-r0/recipe-sysroot/usr/lib//arm-bec-linux-musleabi/8.2.0/../../../include/c++/8.2.0/ext/string_conversions.h:41:
TOPDIR/build/tmp/work/cortexa7t2hf-neon-vfpv4-bec-linux-musleabi/opencv/3.4.3+gitAUTOINC+b38c50b3_1f6d6f0626_bdb7bb85f3_34e4206aef_fccf7cd6a4-r0/recipe-sysroot/usr/lib//arm-bec-linux-musleabi/8.2.0/../../../include/c++/8.2.0/cstdlib:75:15:
fatal error: 'stdlib.h' file not found
              ^~~~~~~~~~
1 error generated.
Signed-off-by: Khem Raj <raj.khem@gmail.com>

* trying to fix the custom AVX2 builder test failures (false alarms)

* fixed compile error with CPU_BASELINE=AVX2 on x86; raised tolerance thresholds in a couple of tests

* fixed compile error with CPU_BASELINE=AVX2 on x86; raised tolerance thresholds in a couple of tests

* fixed compile error with CPU_BASELINE=AVX2 on x86; raised tolerance thresholds in a couple of tests

* seemingly disabled false alarm warning in surf.cpp; increased tolerance thresholds in the tests for SolvePnP and in DNN/ENet

except header file with conversion routines (will be removed in OpenCV 4.0)

via CMake:
- `-DVA_LIBRARIES=/opt/intel/mediasdk/lib64/libva.so.2\;/opt/intel/mediasdk/lib64/libva-drm.so.2`

- tests for both SIMD128 / SIMD256
- different dispatched + baseline(SIMD128) intrinsics

Found via `codespell -q 3 -I ../opencv-whitelist.txt --skip="./3rdparty"`