RFR: 8355233: Add a DMB related benchmark [v2]

[Vladimir Kozlov]

On Mon, 21 Apr 2025 22:19:14 GMT, Eric Caspole <ecaspole at openjdk.org> wrote:

>> In addition to the details in the JBS, I changed the name from DoubleDMB to DMBCheck.
>
> Eric Caspole has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix the copyright header

The comment explaining what is measured would be nice.

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PR Review: https://git.openjdk.org/jdk/pull/24783#pullrequestreview-2784527365