RFR: Increase card offset mask

[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.

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Commit messages:
 - 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

Changes: https://git.openjdk.org/shenandoah/pull/275/files
 Webrev: https://webrevs.openjdk.org/?repo=shenandoah&pr=275&range=00
  Stats: 5 lines in 2 files changed: 2 ins; 1 del; 2 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