RFR: 8278282: G1: Log basic statistics of evacuation failure [v3]

[Hamlin Li]

> The original pr is at #6763 , which should be retired as we have decided to adjust part of optimization solution for evacuation failure (see #6627 for details), so the log will be adjusted accordiingly.
> The basic log related to evacuation failed will looks like below based on this patch.
> 
> 
> [13.126s][debug][gc,phases] GC(0)       Restore Retained Regions (ms): Min:  0.0, Avg: 197.4, Max: 1579.1, Diff: 1579.1, Sum: 1579.1, Workers: 8
> [13.126s][debug][gc,phases] GC(0)         Evacuation Failure Regions:    Min: 1, Avg:  1.0, Max: 1, Diff: 0, Sum: 1, Workers: 1

Hamlin Li has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains three commits:

 - Merge branch 'master' into log-evac-failure-region-num
 - Fix test
 - Initial commit

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Changes: https://git.openjdk.java.net/jdk/pull/6860/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6860&range=02
  Stats: 23 lines in 6 files changed: 16 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6860.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6860/head:pull/6860

PR: https://git.openjdk.java.net/jdk/pull/6860