Fix Illegal instruction (core dumped) on linux system's without AVX

[bobajeff]

This patch add checks to the linux build to check if AVX is available before enabling it and causing Illegal instruction crash on systems that don't have it.

Type

• [ x] Bug fix (non-breaking change which fixes an issue):
  • Fixes Getting Illegal instruction (core dumped) when running Open3D app or import open3d in python #6127
  • Fixes illegal instruction (core dumped) occurs when installing open3d #6087
• 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

Avoid getting Illegal instruction crash when run open3d binary or including the library in python.

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.
• [ x] I will follow up and update the code if CI fails.
• [ x] For fork PRs, I have selected Allow edits from maintainers.

Description

This is essentially hradec's patch turned into a PR. I added a variable for LINUX_X86_64 , so that the linux specific command (lscpu) that checks for AVX, won't affect the Windows build.

[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.