Function polyxml_serialize 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn polyxml_serialize(
    root_name: *const c_char,
    value: *const PolyXmlValue,
    schema: *const PolyXmlSchema,
    indent: i32,
    out_bytes: *mut *mut u8,
    out_len: *mut usize,
) -> PolyXmlErrorCode