Macro std::is_x86_feature_detected

macro_rules! is_x86_feature_detected {
    ($t : tt) => { ... };
}

🔬 This is a nightly-only experimental API. (stdsimd #27731)

This is supported on neither x86 nor x86-64.

Prevents compilation if is_x86_feature_detected is used somewhere else than x86 and x86_64 targets.