Fix: Prevent HACL compilation failure on macOS Silicon when not building universal binaries (#130478)

Problem:

In Python 3.14.0b1, compiling on macOS Silicon without the--enable-universalsdk flag resulted in a compilation error: "unknown type name 'Lib_IntVector_Intrinsics_vec256'". This occurred because the previous fix for a similar issue (#123748,#130366,#129043) in theconfigure andconfigure.ac scripts relied on the$UNIVERSAL_ARCHS variable for conditional checks. However,$UNIVERSAL_ARCHS is only set to "universal2" when--enable-universalsdk is explicitly provided. When this flag is absent (as is the case when only targeting the native arm64 architecture),$UNIVERSAL_ARCHS defaults to "32-bit", causing the conditional logic to fail and the necessary definitions for HACL not to be included.

Solution:

This PR modifies theconfigure andconfigure.ac scripts to use the$build_cpu and$build_vendor variables instead of$UNIVERSAL_ARCHS for determining the target architecture. This approach ensures that the necessary HACL definitions are included when building on macOS with an arm64 architecture, even when--enable-universalsdk is not specified.

The PR provides a quick fix based on$build_cpu and$build_vendor. While functional, this PR aims for a more robust and maintainable solution by directly checking for the "aarch64" architecture in$build_cpu.

Testing:

This fix has been tested successfully on macOS Silicon (arm64) when building Python 3.14.0b1 without the--enable-universalsdk flag. The compilation now completes without the "unknown type name 'Lib_IntVector_Intrinsics_vec256'" error.

• Issue:Compilation of HACL fails under macOS Silicon for version 3.14 #130478