Function safe_app::ffi::mutable_data::mdata_serialised_size

#[no_mangle]
pub unsafe extern "C" fn mdata_serialised_size(
    app: *const App, 
    info_h: MDataInfoHandle, 
    user_data: *mut c_void, 
    o_cb: extern "C" fn(_: *mut c_void, _: FfiResult, _: u64)
)

Get size of serialised mutable data.

Callback parameters: user data, error code, serialised size