RFR: JDK-8264987: G1: Fill BOTs for Survivor-turned-to-Old regions in full gc [v3]

[Hamlin Li]

> in JDK-8262068, we have an enhancement for full gc which will skip compacting some regions with high survivor ratio. There might be some young regions among these skipped regions. These young regions are not filled with BOTs info as they're young.
> But after full GC these young regions will become old regions, and the BOTs info is better to be filled for performance consideration.

Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:

  refine comments, names.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3459/files
  - new: https://git.openjdk.java.net/jdk/pull/3459/files/962e6579..f3524bac

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3459&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3459&range=01-02

  Stats: 10 lines in 1 file changed: 0 ins; 2 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3459.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3459/head:pull/3459

PR: https://git.openjdk.java.net/jdk/pull/3459