RFR: 8369444: JavaFrameAnchor on PPC64 has unnecessary barriers [v2]

[David Briemann]

> No hardware barriers are necessary. All members are volatile and the profiler is run from a signal handler and only observers the thread its running on.

David Briemann has updated the pull request incrementally with one additional commit since the last revision:

  remove whitespace

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27768/files
  - new: https://git.openjdk.org/jdk/pull/27768/files/cb5bbe38..251763d2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27768&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27768&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/27768.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27768/head:pull/27768

PR: https://git.openjdk.org/jdk/pull/27768