RFR: 8303040: linux PPC64le: Implementation of Foreign Function & Memory API (Preview)

[Martin Doerr]

Description will get added soon.

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Commit messages:
 - Initial Panama implementation.

Changes: https://git.openjdk.org/jdk/pull/12708/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12708&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303040
  Stats: 1973 lines in 58 files changed: 1865 ins; 1 del; 107 mod
  Patch: https://git.openjdk.org/jdk/pull/12708.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12708/head:pull/12708

PR: https://git.openjdk.org/jdk/pull/12708