[jdk21u-dev] RFR: 8344414: ZGC: Another division by zero in rule_major_allocation_rate

[Paul Hohensee]

Backport for parity with Oracle 21.0.8.

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Commit messages:
 - Backport 63af2f42b7abe9504897d7c3f3b4cc0b57123694

Changes: https://git.openjdk.org/jdk21u-dev/pull/1602/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1602&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344414
  Stats: 28 lines in 3 files changed: 11 ins; 1 del; 16 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1602.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1602/head:pull/1602

PR: https://git.openjdk.org/jdk21u-dev/pull/1602