RFR: 8288497: add support for JavaThread::cannot_access_oops_safely() [v3]

[Daniel D. Daugherty]

> A fix to add support for JavaThread::is_gc_barrier_detached() which allows
> us to add checks to detect failures like:
> 
>     JDK-8288139 JavaThread touches oop after GC barrier is detached
>     https://bugs.openjdk.org/browse/JDK-8288139
> 
> This fix along with the fix for JDK-8288139 has been tested in Mach5 Tier[1-8].
> There are no related failures in Mach5 Tier[1-7]; Mach5 Tier8 is still running.

Daniel D. Daugherty has updated the pull request incrementally with one additional commit since the last revision:

  Rename cannot_access_oops_safely to is_oop_safe and invert the function's logic.

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

Changes:
  - all: https://git.openjdk.org/jdk19/pull/20/files
  - new: https://git.openjdk.org/jdk19/pull/20/files/24ecdea4..3f526bee

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk19&pr=20&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk19&pr=20&range=01-02

  Stats: 5 lines in 2 files changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk19/pull/20.diff
  Fetch: git fetch https://git.openjdk.org/jdk19 pull/20/head:pull/20

PR: https://git.openjdk.org/jdk19/pull/20