* added support for Eigen cross-compilation

* cmake: fix Eigen detection

- CPU_DISPATCH_FINAL should be used for filtering

* core: improve AVX512 infrastructure by adding more CPU features groups

* cmake: use groups for AVX512 optimization flags

* core: remove gap in CPU flags enumeration

* cmake: restore default CPU_DISPATCH

backporting commit c9f3f4d1

BUG: Qt5 components not correctly detected if only Qt5_DIR is provided, when this is supported by Qt CMake system.

Fixed by updating Qt5 find_package call to use modern CMake syntax

fixes build with VTK

- drop legacy check_module() macro
- drop 'ALIASOF_'

Adds IMPORTED for the TBB::tbb alias target as otherwise cmake produces
the following error:

CMake Error: install(EXPORT "OpenCVModules" ...) includes target "opencv_core" which requires target "tbb" that is not in the export set.

This problem occurs with the defaults used by homebrew on macOS, which
compiles both static and shared versions of TBB and OpenCV.

process defines from INTERFACE targets

cmake: fix WITH_OPENCL_D3D11_NV check

- use relative paths for includes
- fix PCH generation with GCC (dummy file has been used)

* Add CUDA support for D3D11 interop. #13888

color_detail.hpp: fixed build error : dynamic initialization is not supported for a __constant__ variable.
directx.cpp: Add CUDA support(cl_nv_d3d11_sharing) for D3D11 interop.  #13888

Update directx.cpp

Format adjustment.

Update directx.cpp

fix error.

Update directx.cpp

Format adjustment

Update directx.cpp

fix trailing whitespace.

fix format errors

convert indentation to spaces .
Trim trailing whitespace.
Add information about source of cl_d3d11_ext.h
Avoid unrelated changes.

Increase compile-time conditional judgment.

Increase the judgment of whether the OCL device has the required extensions at compile time.

Add compilation option  `HAVE_CLNVEXT`.Check CL support in runtime.

Check result of `clGetExtensionFunctionAddressForPlatform` for KHR is invalid.It always can get the address(from OpenCL.dll),So I check NV support(from nvopencl64.dll) before KHR when `HAVE_CLNVEXT` is enabled.

Delete cl_d3d11_ext.h

Modified parameter list

fix "cannot open include file: 'CL/cl_d3d11_ext.h'"

 remove not referenced var

fix C2143: syntax error

Improve compile-time judgment.

dlrectx.cpp Modify the detection order.
initializeContextFromD3D11Device:
```
    // try with NV(Need to check it first)
    // try with KHR
```

fix warnig C4100

Revert "fix warnig C4100"

This reverts commit 76e5becb67780071d0cbde61cc4f5f807ad7c5ac.

fix warning C4100

fix warning C4505

Format alignment

Format adjustment and automatically detect header files.

Automatically detect header files when users are not configured or configuration errors occur.

avoid unrelated changes.

Update .cmake

Update .cmake

* fix build errors

* fix warning:defined but not used

* Revert "fix warning:defined but not used"

This reverts commit 7ab3537cd070f89b15bc2926e4ac9ec74c84a122.

* fix warning:defined but not used

* fix build error for mac

* fix build error for win

* optimizing branch judgment

* Revert "optimizing branch judgment"

This reverts commit 88b72b870ec13fd26f64a5ac374484c5cfe80854.

* fix warning C4702: unreachable code

* remove unused code

* Fix problems that may lead to undefined behavior

* Add status check

* fix error C2664,C2665 : cannot convert argument

* Format adjustment

VSCODE will automatically format the indentation to 4 spaces in some situation.

* fix error C2440

* fix error C2440

* add cl_d3d11_ext.h

* Format adjustment

* remove unnecessary checks

The Android NDK 16b has a bug that sets the ANDROID_NDK_REVISION
variable incorrectly, generating an unexpected line break in the
middle of the string. This breaks the build as the generated
version_string.inc presents an invalid C string.

Remove leading and trailing line breaks, warns for line breaks in the
middle of 'msg' and escape them before appending to
OPENCV_BUILD_INFO_STR.

 - allow cmake to check sanity of vsx aligned ld/st
 - force universal intrinsics v_load_aligned/v_store_aligned
   to failback to unaligned ld/st if cmake runtime vsx aligned test fail

* Enabled -Wnarrowing warning

* Fixed type narrowing issues

* Cast python constants

* Use long long for python constants

* Use int for python constants with fallback to long

* Update cv2.cpp

https://software.intel.com/en-us/openvino-toolkit

* 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