RFR: 8268556: Use bitmap for storing regions that failed evacuation

[Thomas Schatzl]

Hi all,

  can I have reviews for this follow-up cleanup of the earlier JDK-8267073? It introduced a byte-map for storing information about regions that have already been experienced an evacuation failure.

During review the improvement to use a bitmap instead came up - uses less space and there are existing setters/getters that can be used.

Testing: tier1-4

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.java.net/jdk/pull/4471/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4471&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268556
  Stats: 13 lines in 3 files changed: 2 ins; 5 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4471.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4471/head:pull/4471

PR: https://git.openjdk.java.net/jdk/pull/4471