RFR: 8350075: Performance difference between SegmentAllocator methods [v2]

[Per Minborg]

> This PR proposes to add `@ForceInline` to the `default` methods in `SegmentAllocator` that do not already have it.

Per Minborg 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 three additional commits since the last revision:

 - Add benchmark
 - Merge branch 'master' into ms-add-missing-force-inline
 - Add @ForceInline to default methods

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/23628/files
  - new: https://git.openjdk.org/jdk/pull/23628/files/a4be5572..8b44d78d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23628&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23628&range=00-01

  Stats: 195415 lines in 4444 files changed: 89076 ins; 81873 del; 24466 mod
  Patch: https://git.openjdk.org/jdk/pull/23628.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23628/head:pull/23628

PR: https://git.openjdk.org/jdk/pull/23628