RFR: 8343188: Investigate ways to simplify MemorySegment::ofBuffer [v2]

[Per Minborg]

> This PR proposes to improve `MemorySegment::ofBuffer` making it more amenable to inlining and generally improving performance.
> 
> Testing successfully on tier1-3

Per Minborg has updated the pull request incrementally with one additional commit since the last revision:

  Update from comments and add benchmark

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21764/files
  - new: https://git.openjdk.org/jdk/pull/21764/files/c430801d..fd9a7b60

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21764&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21764&range=00-01

  Stats: 104 lines in 6 files changed: 76 ins; 23 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/21764.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21764/head:pull/21764

PR: https://git.openjdk.org/jdk/pull/21764