RFR: 8324613: Serial: Rename GenerationPool to TenuredGenerationPool [v2]

[Albert Mingkun Yang]

> Trivial renaming to use concrete subtype.

Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:

  review

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17551/files
  - new: https://git.openjdk.org/jdk/pull/17551/files/15114d69..da42514e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17551&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17551&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/17551.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17551/head:pull/17551

PR: https://git.openjdk.org/jdk/pull/17551