RFR: Use static assert to validate card offset encoding mask [v2]

[William Kemper]

> Follow up to https://github.com/openjdk/shenandoah/pull/275 - replace runtime assert with static assert.

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

  Document source for max card size

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Changes:
  - all: https://git.openjdk.org/shenandoah/pull/279/files
  - new: https://git.openjdk.org/shenandoah/pull/279/files/6c25a665..ff91daba

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=shenandoah&pr=279&range=01
 - incr: https://webrevs.openjdk.org/?repo=shenandoah&pr=279&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/shenandoah/pull/279.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/279/head:pull/279

PR: https://git.openjdk.org/shenandoah/pull/279