[build] Fix GLUT dependency handling on Windows

[jslee02]

The detection of GLUT is already handled by dart_check_optional_package() (will skip building the osg component), so there is no need to check it again. Additionally, the logic if(NOT WIN32 OR CYGWIN) is inconsistent.

As a result, FindDARTGLUT.cmake is not installed on Windows:

Linux:
https://dev.azure.com/conda-forge/feedstock-builds/_build/results?buildId=969952&view=logs&j=656edd35-690f-5c53-9ba3-09c10d0bea97&t=986b1512-c876-5f92-0d81-ba851554a0a3&l=1964

Windows:
https://dev.azure.com/conda-forge/feedstock-builds/_build/results?buildId=969952&view=logs&j=a70f640f-cc53-5cd3-6cdc-236a1aa90802&t=6119ccbe-9301-594f-7c27-f792b80a7fcc&l=2373

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Before creating a pull request

• Document new methods and classes
• Format new code files using ClangFormat by running make format
• Build with -DDART_TREAT_WARNINGS_AS_ERRORS=ON and resolve all the compile warnings

Before merging a pull request

• Set version target by selecting a milestone on the right side
• Summarize this change in CHANGELOG.md
• Add unit test(s) for this change
• Add Python bindings for new methods and classes

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.56%. Comparing base (4878e77) to head (6fd87e3).
Report is 9 commits behind head on release-6.14.

Additional details and impacted files

@@              Coverage Diff              @@
##           release-6.14    #1827   +/-   ##
=============================================
  Coverage         61.56%   61.56%           
=============================================
  Files               490      490           
  Lines             46021    46021           
=============================================
  Hits              28332    28332           
  Misses            17689    17689           

[jslee02]

Confirmed that DARTFindGLUT.cmake is installed on Windows