RFR: 8377442: More fixes to ThreadLocalAllocBuffer after JDK-8377179

[Thomas Schatzl]

Hi all,

  please review these additional changes to TLAB code after @kimbarret's comments.

Some typos, some improvements to const'ness, one really embarassing new race added (and fixed).

Testing: gha

Thanks,
  Thomas

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Commit messages:
 - * improve text
 - * more documentation why using AtomicAccess
 - * more commenting
 - * comment
 - * more issues
 - 8377179

Changes: https://git.openjdk.org/jdk/pull/29626/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29626&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8377442
  Stats: 15 lines in 5 files changed: 6 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/29626.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29626/head:pull/29626

PR: https://git.openjdk.org/jdk/pull/29626