Function str_convert 

pub unsafe extern "C" fn str_convert(
    s: *mut str,
    charsetin: c_int,
    latexin: c_int,
    utf8in: c_int,
    xmlin: c_int,
    charsetout: c_int,
    latexout: c_int,
    utf8out: c_int,
    xmlout: c_int,
) -> c_int