RFR: 8290376: G1: Refactor G1MMUTracker::when_sec

Fri Jul 15 14:22:30 UTC 2022

Introducing a more intuitive implementation.

This PR consists of two commits: the first adds the new algorithm and verifies the result is same as before. The second commit removes the old implementation.

Test: tier1-6 for the first commit.

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Commit messages:
 - replace
 - g1-mmu

Changes: https://git.openjdk.org/jdk/pull/9517/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9517&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8290376
  Stats: 61 lines in 2 files changed: 25 ins; 17 del; 19 mod
  Patch: https://git.openjdk.org/jdk/pull/9517.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9517/head:pull/9517

PR: https://git.openjdk.org/jdk/pull/9517