Constant core::arch::x86::_MM_FROUND_FLOOR

pub const _MM_FROUND_FLOOR: i32 = _MM_FROUND_RAISE_EXC | _MM_FROUND_TO_NEG_INF; // 1i32

This is supported on (non-crate feature miri-test-libstd or test or doctest) and x86 only.

round down and do not suppress exceptions