core\eigen.hpp is missing #ifndef check before forcing #define NOMINMAX.
Causes compile fails on MSVC with flags for high standards.

The bug was introduced by #17578 as attempt to fix #17548

[build] [26/28  57% :: 23.268] C:\PROGRA~2\MICROS~2\2019\COMMUN~1\VC\Tools\MSVC\1429~1.301\bin\Hostx64\x64\cl.exe  ...
[build] FAILED: CMakeFiles/......obj 
[build] Microsoft (R) C/C++ Optimizing Compiler Version 19.29.30140 for x64
[build] Copyright (C) Microsoft Corporation.  All rights reserved.
[build] C:\...\Release\include\opencv2/core/eigen.hpp(55): error C2220: the following warning is treated as an error
[build] C:\...\Release\include\opencv2/core/eigen.hpp(55): warning C4005: 'NOMINMAX': macro redefinition
[build] command line(1): note: see previous definition of 'NOMINMAX'
...
[build] ninja: build stopped: subcommand failed.
[build] Build finished with exit code 1

System information (version)

• OpenCV => 4.5.4, 4.5.5, and further
• Operating System / Platform => all, but this surfaces most easily in MSVC
• Compiler => MSVC

Detailed description

As above. Missing #ifndef surrounding the #define

Steps to reproduce

Review the code.

Fix

trivial

#ifndef NOMINMAX
#define NOMINMAX // fix https://github.com/opencv/opencv/issues/17548
#endif

Issue submission checklist

• I report the issue, it's not a question
• I checked the problem with documentation, FAQ, open issues,
  forum.opencv.org, Stack Overflow, etc and have not found any solution
• I updated to the latest OpenCV version and the issue is still there