fix: remove forced SSE4.2 from x64 builds

[Brooooooklyn]

Published CRC32 addons crash during module registration on older x64 CPUs without SSSE3. The global +sse4.2 compiler flag permits unsupported instructions throughout the addon and makes SSE4.2 feature checks unconditionally true.

Remove the forced feature from Linux GNU and Windows MSVC x64 builds. crc32fast and crc32c already select accelerated implementations at runtime, so newer CPUs retain hardware acceleration while older CPUs can use the software paths.

Fixes #1016.

Validation:

• Reproduced SIGILL in published GNU x64 versions 1.10.6 and 1.10.7 under QEMU's Opteron G3 model; GDB confirmed pshufb as the faulting instruction in 1.10.6.
• Rebuilt the GNU x64 addon with Rust 1.98.1 and tested it using Node 18.20.8 under Opteron G3, qemu64 with SSSE3/SSE4.1/SSE4.2/PCLMUL disabled, and max.
• All three CPU models pass module loading, standard CRC vectors, 324 buffer cases covering lengths, alignment and initial states, incremental checksums, and UTF-8 string inputs.
• Confirmed the rebuilt binary still contains accelerated CRC32 and PCLMUL instructions. Formatting and whitespace checks pass.

Runtime validation used Linux CPU emulation. Native Windows execution and physical older-CPU testing were not performed.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-10T03:13:13.597267Z	2490362	PR opened

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