Function _nfloat_complex_vec_add 

pub unsafe extern "C" fn _nfloat_complex_vec_add(
    res: nfloat_complex_ptr,
    x: nfloat_complex_srcptr,
    y: nfloat_complex_srcptr,
    len: slong,
    ctx: *mut gr_ctx_struct,
) -> c_int