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

[Eric Caspole]

> 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

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/24783/files
  - new: https://git.openjdk.org/jdk/pull/24783/files/0a3427e0..312cb317

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24783&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24783&range=00-01

  Stats: 5 lines in 1 file changed: 1 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/24783.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24783/head:pull/24783

PR: https://git.openjdk.org/jdk/pull/24783