cpu::intel: Do CPU feature detection in Rust.

[briansmith]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 88.42105% with 11 lines in your changes missing coverage. Please review.

Project coverage is 96.61%. Comparing base (e5fe160) to head (86837a3).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/cpu/intel.rs	88.42%	9 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2346   +/-   ##
=======================================
  Coverage   96.61%   96.61%           
=======================================
  Files         176      175    -1     
  Lines       21640    21605   -35     
  Branches      529      515   -14     
=======================================
- Hits        20907    20874   -33     
- Misses        618      626    +8     
+ Partials      115      105   -10     

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[briansmith]

It looks like Rust 1.63..=1.65 may contain bugs in __cpuid: rust-lang/rust#101861 so we may need to vendor a newer version of __cpuid or do another workaround.

[briansmith]

It looks like Rust 1.63..=1.65 may contain bugs in __cpuid: rust-lang/rust#101861 so we may need to vendor a newer version of __cpuid or do another workaround.

We should check what the latest versions of stdarch do and what libstd is using. Maybe we can look into workarounds used by other projects to use these safely.

[briansmith]

This has two commits; the first is PR #2352. When PR #2352 gets merged, I will rebase this.

[Edit: Rebased]