fix(ios): define BLAKE3_NO_* macros for x86_64 simulator

[stefan-garofalo]

Summary

Companion to #884. That PR excluded blake3_neon.c for x86_64 simulator (compile-time fix), but x86 SIMD symbols (AVX-512, AVX2, SSE4.1, SSE2) still cause linker errors:

Undefined symbols for architecture x86_64:
  _blake3_compress_in_place_avx512
  _blake3_compress_in_place_sse2
  _blake3_compress_in_place_sse41
  _blake3_compress_xof_avx512
  ...

The .c implementation files (blake3_avx512.c, etc.) are correctly excluded via exclude_files, but blake3_dispatch.c still references those symbols — it forward-declares and calls them unless BLAKE3_NO_* macros are defined:

#if !defined(BLAKE3_NO_AVX512)
  if (features & AVX512VL) {
    blake3_compress_in_place_avx512(cv, block, block_len, counter, flags);
    return;
  }
#endif

Android's CMakeLists.txt already handles this (lines 18-22) with -DBLAKE3_NO_AVX512 -DBLAKE3_NO_AVX2 ..., but the iOS podspec doesn't.

This PR adds conditional GCC_PREPROCESSOR_DEFINITIONS scoped to [sdk=iphonesimulator*][arch=x86_64], mirroring the Android approach. Blake3 falls back to its portable C implementation (the SIMD paths were never reachable on the simulator anyway).

• Device builds (ARM64): unaffected — scoped to simulator SDK only
• ARM64 simulator: unaffected — scoped to x86_64 arch only

Related

• Fixes iOS x86_64 simulator: undefined BLAKE3 SIMD symbols (AVX-512, AVX2, SSE) on v1.0.9 #918
• Companion to fix(ios): exclude blake3_neon on x86_64 simulator #884

Testing

• Applied this fix as a pnpm patch on v1.0.9, ran EAS Build with development-simulator profile (x86_64 iOS Simulator) — build now succeeds where it previously failed with undefined symbols

[boorad]

thanks!