[jdk17u] RFR: 8274851: [ppc64] Port zgc to linux on ppc64le

[Martin Doerr]

Clean backport of JDK-8274851.

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Commit messages:
 - Backport 337b73a459ba24aa529b7b097617434be1d0030e

Changes: https://git.openjdk.java.net/jdk17u/pull/202/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=202&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274851
  Stats: 1273 lines in 11 files changed: 1265 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/202.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/202/head:pull/202

PR: https://git.openjdk.java.net/jdk17u/pull/202