RFR: 8320622: [TEST] Improve coverage of compiler/loopopts/superword/TestMulAddS2I.java on different platforms

[Fei Gao]

It would be worthwhile to improve the test coverage on all platforms by applying another common VM flag.

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Commit messages:
 - 8320622: [TEST] Improve coverage of compiler/loopopts/superword/TestMulAddS2I.java on different platforms

Changes: https://git.openjdk.org/jdk/pull/19305/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19305&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320622
  Stats: 7 lines in 1 file changed: 0 ins; 4 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/19305.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19305/head:pull/19305

PR: https://git.openjdk.org/jdk/pull/19305