RFR: Increase card offset mask [v2]

[William Kemper]

> On 32-bit platforms, a 512 byte card covers 128 words. On 64-bit platforms, a 1024 byte card (the maximum allowed) also covers 128 words. This change increases the size of the mask we use when encoding object start offsets to handle these situations.

William Kemper has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Merge branch 'openjdk:master' into increase-card-offset-mask
 - Re-problem-list failing pipeline tests
 - Re-problem-list failing GHA tests
 - Increase card offset mask to cover 32-bit words and/or 1k cards

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Changes:
  - all: https://git.openjdk.org/shenandoah/pull/275/files
  - new: https://git.openjdk.org/shenandoah/pull/275/files/9280938f..8848cf2e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=shenandoah&pr=275&range=01
 - incr: https://webrevs.openjdk.org/?repo=shenandoah&pr=275&range=00-01

  Stats: 34672 lines in 716 files changed: 20167 ins; 8751 del; 5754 mod
  Patch: https://git.openjdk.org/shenandoah/pull/275.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/275/head:pull/275

PR: https://git.openjdk.org/shenandoah/pull/275