RFR: 8338546: Speed up ConstantPoolBuilder::classEntry(ClassDesc) [v2]

[Chen Liang]

> Speed up `ConstantPoolBuilder::classEntry(ClassDesc)` by going through `ClassDesc` comparison and reusing descriptor hash to calculate internal name hash if possible. No suitable device to run benchmarks so need to find something to run the new benchmark to ensure things work as intended.

Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Improve benchmark as suggested
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/classentry-speedup
 - Fix microbenchmark
 - Improve jmh
 - 8338546: Speed up ConstantPoolBuilder::classEntry(ClassDesc)

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20667/files
  - new: https://git.openjdk.org/jdk/pull/20667/files/9862ccb2..da9c6d82

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20667&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20667&range=00-01

  Stats: 1904 lines in 24 files changed: 1796 ins; 51 del; 57 mod
  Patch: https://git.openjdk.org/jdk/pull/20667.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20667/head:pull/20667

PR: https://git.openjdk.org/jdk/pull/20667