RFR: 8328278: Do not print the tenuring threshold in 'AgeTable::print_on' [v3]

[Guoxiong Li]

> Hi all,
> 
> This patch places the SerialGC code that computes tenuring threshold before per GC instead of after per GC, so that the method `AgeTable::print_on` prints the right tenuring threshold. Just like the current G1 implementation.
> 
> Thanks for taking the time to review.
> 
> Best Regards,
> -- Guoxiong

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

  Fix test TestAgeOutput.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18329/files
  - new: https://git.openjdk.org/jdk/pull/18329/files/d8945592..31caa031

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18329&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18329&range=01-02

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/18329.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18329/head:pull/18329

PR: https://git.openjdk.org/jdk/pull/18329