RFR: 8370822: Improve performance for MemorySegment::fill

[Igor Rudenko]

The manual byte-replication expression replaced with the multiplicative expansion trick - a more compact and efficient equivalent.

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Commit messages:
 - 8370822: Improve performance for MemorySegment::fill

Changes: https://git.openjdk.org/jdk/pull/28031/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28031&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370822
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/28031.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28031/head:pull/28031

PR: https://git.openjdk.org/jdk/pull/28031