RFR: 8375093: Convert GlobalCounter to use Atomic<T>

[Kim Barrett]

Please review this change to make GlobalCounter use Atomic instead of
AtomicAccess.

Testing: mach5 tier1

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Commit messages:
 - fix

Changes: https://git.openjdk.org/jdk/pull/29256/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29256&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8375093
  Stats: 24 lines in 5 files changed: 3 ins; 1 del; 20 mod
  Patch: https://git.openjdk.org/jdk/pull/29256.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29256/head:pull/29256

PR: https://git.openjdk.org/jdk/pull/29256