Adds missing asyncMeta during VNode cloning

[luisatmaniak]

What kind of change does this PR introduce? (check at least one)

• Bugfix

Does this PR introduce a breaking change? (check one)

• No

The PR fulfills these requirements:

• It's submitted to the dev branch for v2.x (or to a previous version branch), not the master branch
• All tests are passing: https://github.com/vuejs/vue/blob/dev/.github/CONTRIBUTING.md#development-setup

Other information:
This fixes a crash during SSR, where a parent functional component is using an async component in the render function. If the prop is not copied, renderAsyncComponent crashes during rendering. Looks like this bug was introduced in 62a922e

[yyx990803]

Thanks for the fix, is it possible to provide a reproduction for the case so we can better determine if this fix is sufficient?

[yyx990803]

I merged it because asyncMeta indeed should be copied, but if possible, I'd still love to see a reproduction of the case so that we can be sure this fix covers the bug properly. Thanks.