[jdk17u-dev] RFR: 8298138: Shenandoah: HdrSeq asserts "sub-bucket index (512) overflow for value ( 1.00)"

[Aleksey Shipilev]

Clean backport to eliminate a corner case in Shenandoah accounting code.

Testing:
 - [ ] Linux AArch64 fastdebug gtests
 - [ ] Linux AArch64 fastdebug `hotspot_gc_shenandoah`

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Commit messages:
 - Backport c16eb89ce0d59f2ff83b6db0bee3e384ec8d5efe

Changes: https://git.openjdk.org/jdk17u-dev/pull/1408/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1408&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8298138
  Stats: 77 lines in 3 files changed: 74 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1408.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1408/head:pull/1408

PR: https://git.openjdk.org/jdk17u-dev/pull/1408