RFR: 8311630: [s390] Implementation of Foreign Function & Memory API (Preview)

[sid8606]

Implementation of "Foreign Function & Memory API" for s390x.

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Commit messages:
 - Fix whitespace errors and boilerplate text
 - 8311630:[s390] Implementation of Foreign Function & Memory API (Preview)

Changes: https://git.openjdk.org/jdk/pull/14801/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14801&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311630
  Stats: 1630 lines in 20 files changed: 1567 ins; 3 del; 60 mod
  Patch: https://git.openjdk.org/jdk/pull/14801.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14801/head:pull/14801

PR: https://git.openjdk.org/jdk/pull/14801