Function _fcvt_s 

pub unsafe extern "C" fn _fcvt_s(
    _DstBuf: *mut c_char,
    _Size: size_t,
    _Val: f64,
    _NumOfDec: c_int,
    _PtDec: *mut c_int,
    _PtSign: *mut c_int,
) -> errno_t