Add a down-prioritized relaxed-SIMD variant of openblas-experimental

[jjerphan]

Template B: Checklist for updating a package

• ⚠️ Bump build number if the version remains unchanged
• Or reset build number to 0 if updating the package to a newer version

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PR Formatting

• PR title follows format: Add [package-name] or Update [package-name] to [version]
• PR description includes:
  • Version being added/updated
  • Any special build considerations or patches applied

Package Details

• Package Name: openblas (from openblas-experimental)
• Version: 0.3.35.dev0 (build 3), snapshot of OpenMathLib/OpenBLAS develop @ b4100af

Build Notes

Add a second WASM build variant for OpenBLAS #6020 relaxed SIMD, following the conda-forge OpenBLAS named-build-string pattern (openmp / pthreads):

Variant	openblas_wasm_relaxed_simd	Build string	Solver priority
Portable SIMD128 (default)	0	simd128_h…_3	preferred
Relaxed SIMD / FMA	1	relaxed_simd_h…_3	down_prioritize_variant: 1

Users select explicitly, for example:

dependencies:
  - openblas=0.3.35* *simd128*        # portable default
  - openblas=0.3.35* *relaxed_simd*   # requires engine support

WASM_RELAXED_SIMD is passed through to Make from the variant. The relaxed-SIMD module will not instantiate on engines without the feature (notably shipping Safari / JavaScriptCore); see OpenBLAS docs.

The package version string is unchanged, so the build number is bumped to 3.

Patches

Unchanged (still the 11 emforge patches on b4100af).