RFR: 8357976: GenShen crash in swap_card_tables: Should be clean [v2]

[William Kemper]

> Degenerated cycles must also clean the `read` card table before swapping it with the `write` card table.

William Kemper has updated the pull request incrementally with one additional commit since the last revision:

  Consolidate read table cleaning

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/25735/files
  - new: https://git.openjdk.org/jdk/pull/25735/files/5e2c20a8..9552021c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25735&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25735&range=00-01

  Stats: 20 lines in 3 files changed: 5 ins; 10 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/25735.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25735/head:pull/25735

PR: https://git.openjdk.org/jdk/pull/25735