RFR: 8277736: G1: Configure the distribution of objects failing evacuation among regions

[Hamlin Li]

Currently, debug options of evacuation failure, like G1EvacuationFailureALotInterval and G1EvacuationFailureALotCount only config the ratio of objects failing evacuation, basically the distribution of objects failing evacuation is even among regions.

JDK-8256265 is trying to improve parallelism in regions that failed evacuation, it'll be helpful if there is option to config the distribution of objects failing evacuation among regions, so implementation of JDK-8256265 could be profiled more precisely.

This is to add the support and necessary vm options.

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Commit messages:
 - Fix compilation error; refine code
 - Initial commit

Changes: https://git.openjdk.java.net/jdk/pull/6561/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6561&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8277736
  Stats: 51 lines in 6 files changed: 44 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6561.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6561/head:pull/6561

PR: https://git.openjdk.java.net/jdk/pull/6561