RFR: Update copyright lines

[Aleksey Shipilev]

On Thu, 6 Apr 2023 14:26:17 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> This updates copyright lines on all files Generational Shenandoah touches related to upstream.
> 
> Generally, every change should come with actual copyright line. It is agreed in upstream to upgrade the Oracle copyright years, and that is usually required for every incoming PR.
> 
> I used a simple ruleset:
>   - If the change is small and there is Oracle header, the date is updated to 2023;
>   - If the change is small and there only Red Hat header (which we cannot touch), Amazon header is added;
>   - If the change is large, Amazon header is added and Oracle header is updated to 2023;
> 
> It reverts some of the changes related to upstream, if they do not fit the ruleset above.
> Also, existing Amazon headers are updated to new, consistent form.

Thank you! Since this does not change the product code, and amendments could be done after this integration, I am integrating now.

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PR Comment: https://git.openjdk.org/shenandoah/pull/247#issuecomment-1499351635