RFR: 8343844: Add benchmarks for superword/autovectorization in FFM BulkOperations

[Per Minborg]

This PR proposed to add a few benchmarks using  superword/autovectorization

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Commit messages:
 - Add benchmarks

Changes: https://git.openjdk.org/jdk/pull/21988/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21988&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8343844
  Stats: 36 lines in 1 file changed: 36 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21988.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21988/head:pull/21988

PR: https://git.openjdk.org/jdk/pull/21988