RFR: 8254814: [Vector API] Fix an AVX512 crash after JDK-8223347

[Jie Fu]

As discussed here[1], it's time to integrate this fix.
And the original PR is here[2].

Testing:
  - All jdk/incubator/vector/ tests passed on Linux/x64 AVX512 machines

[1] https://github.com/openjdk/jdk/pull/367#issuecomment-701560441
[2] https://github.com/openjdk/panama-vector/pull/1

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Commit messages:
 - 8254814: [Vector API] Fix an AVX512 crash after JDK-8223347

Changes: https://git.openjdk.java.net/jdk/pull/676/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=676&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254814
  Stats: 22 lines in 1 file changed: 0 ins; 20 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/676.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/676/head:pull/676

PR: https://git.openjdk.java.net/jdk/pull/676