[jdk17u-dev] RFR: 8314935: Shenandoah: Unable to throw OOME on back-to-back Full GCs

[William Kemper]

Backport was unclean, but trivially resolved `nullptr`/`NULL` conflict.

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Commit messages:
 - Backport 716201c77d160dc78db61957aa002eef71641688

Changes: https://git.openjdk.org/jdk17u-dev/pull/1724/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1724&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314935
  Stats: 22 lines in 2 files changed: 5 ins; 11 del; 6 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1724.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1724/head:pull/1724

PR: https://git.openjdk.org/jdk17u-dev/pull/1724