Function polyxml_schema_builder_add_field 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn polyxml_schema_builder_add_field(
    builder: *mut PolyXmlSchemaBuilder,
    name: *const c_char,
    xml_name: *const c_char,
    kind: PolyXmlFieldKind,
    scalar_type: PolyXmlScalarType,
)