RFR: Update alloc liveness data during final mark of old generation

[William Kemper]

Final mark for old generation was missing the use of `ShenandoahFinalMarkUpdateRegionStateClosure` to update region liveness data with allocated objects. In some cases, this could lead to objects being promoted into old regions that appear to have no live data resulting in these promoted objects being erroneously collected.

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Commit messages:
 - Update alloc liveness data during final mark of old generation

Changes: https://git.openjdk.java.net/shenandoah/pull/60/files
 Webrev: https://webrevs.openjdk.java.net/?repo=shenandoah&pr=60&range=00
  Stats: 42 lines in 5 files changed: 32 ins; 5 del; 5 mod
  Patch: https://git.openjdk.java.net/shenandoah/pull/60.diff
  Fetch: git fetch https://git.openjdk.java.net/shenandoah pull/60/head:pull/60

PR: https://git.openjdk.java.net/shenandoah/pull/60