RFR: JDK-8265928: G1: Update copyright in several files

[Hamlin Li]

On Mon, 26 Apr 2021 02:36:13 GMT, Hamlin Li <mli at openjdk.org> wrote:

> I missed update the copyrights in several files, and per suggested in https://github.com/openjdk/jdk/pull/2379#pullrequestreview-584943730, it's better to update them in a separate CR, this is the one to fix them in a batch.

Thanks Thomas for your review.

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PR: https://git.openjdk.java.net/jdk/pull/3682