RFR: 8271870: G1: Add objArray splitting when scanning object with evacuation failure [v2]

[Thomas Schatzl]

> Hi all,
> 
>   please review this change that makes the object iteration path for evacuation failed objects the same as the one for regular objects (and indeed make both use the same code).
> 
> This has been made possible with the refactoring of object array task queues.
> 
> At the same time this also covers [JDK-8271871](https://bugs.openjdk.org/browse/JDK-8271871).
> 
> Testing: tier1-5, some perf testing with no differences
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  * some additional assert to make sure the scanner is initialized correctly.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24222/files
  - new: https://git.openjdk.org/jdk/pull/24222/files/e5ce3984..21cc754a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24222&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24222&range=00-01

  Stats: 7 lines in 2 files changed: 6 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/24222.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24222/head:pull/24222

PR: https://git.openjdk.org/jdk/pull/24222