RFR: 8336827: compiler/vectorization/TestFloat16VectorConvChain.java timeouts on ppc64 platforms after JDK-8335860

[Matthias Baesken]

After [JDK-8335860](https://bugs.openjdk.org/browse/JDK-8335860), we see a lot of timeouts in test compiler/vectorization/TestFloat16VectorConvChain.java
on the ppc64 based platforms.
The timeouts show up especially with the (fast)debug binaries.

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Commit messages:
 - JDK-8336827

Changes: https://git.openjdk.org/jdk/pull/20276/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20276&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336827
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/20276.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20276/head:pull/20276

PR: https://git.openjdk.org/jdk/pull/20276