RFR: 8351921: G1: Pinned regions with pinned objects only reachable by native code crash VM

[Thomas Schatzl]

Hi all,

  please review this clean backout of "8351921: G1: Pinned regions with pinned objects only reachable by native code crash VM".

The original patch is incomplete, and the new patch is basically a rewrite apart from the regression test.

This reverts commit 558c015c995dbe65d876c1c5761030588773271c.

Thanks,
  Thomas

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Commit messages:
 - 8351921

Changes: https://git.openjdk.org/jdk/pull/24146/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24146&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351921
  Stats: 123 lines in 4 files changed: 7 ins; 108 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/24146.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24146/head:pull/24146

PR: https://git.openjdk.org/jdk/pull/24146