RFR: Use CardTable::card_size_in_words rather than hard coded constant [v4]

[Kelvin Nilsen]

On Mon, 19 Dec 2022 21:21:47 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> Calculation assumed 64 words per card, which does not hold on 32 bit word platforms. The number of words per card also depends on `GCCardSizeInBytes` command line parameter.
>
> William Kemper has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove stale comment

Thanks.

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Marked as reviewed by kdnilsen (Committer).

PR: https://git.openjdk.org/shenandoah/pull/186