RFR: 8263260: [s390] Support latest hardware (z14 and z15)

[Lutz Schmidt]

8263260: [s390] Support latest hardware (z14 and z15)

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Commit messages:
 - 8263260: [s390] Support latest hardware (z14 and z15)

Changes: https://git.openjdk.java.net/jdk/pull/2918/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2918&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263260
  Stats: 133 lines in 2 files changed: 67 ins; 39 del; 27 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2918.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2918/head:pull/2918

PR: https://git.openjdk.java.net/jdk/pull/2918