Use GLIBCXX_USE_CXX11_ABI by default

[QuentinTorg]

Set the GLIBCXX_USE_CXX11_ABI ON as default independent of the value of BUILD_SYCL_MODULE

Type

• Bug fix (non-breaking change which fixes an issue): Fixes Errors occur when Open3D library is linked together with other libraries, e.g. gflags, opencv #2286, Fixes Open3d will make the functions related to polygon in pcl unable to be found #3515
• New feature (non-breaking change which adds functionality). Resolves #
• Breaking change (fix or feature that would cause existing functionality to not work as expected) Resolves #

Motivation and Context

Previously the CXX11 ABI was off by default. #4387 was merged to fix this issue. Later, a regression was introduced with #5081 that made the default CXX11 ABI conditional on another variable. This once again changed the default CXX11 ABI back to the problematic case if no parameter was specified

Checklist:

• I have run python util/check_style.py --apply to apply Open3D code style
  to my code.
• This PR changes Open3D behavior or adds new functionality.
  • Both C++ (Doxygen) and Python (Sphinx / Google style) documentation is
    updated accordingly.
  • I have added or updated C++ and / or Python unit tests OR included test
    results (e.g. screenshots or numbers) here.
• I will follow up and update the code if CI fails.
• For fork PRs, I have selected Allow edits from maintainers.

Description

This PR removes the conditional check so that the CXX11 ABI will be used by default

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This change is 

[update-docs]

Thanks for submitting this pull request! The maintainers of this repository would appreciate if you could update the CHANGELOG.md based on your changes.

[ssheorey]

Hi @QuentinTorg thanks for the bug fix!