[lilliput-jdk17u:lilliput] RFR: 8308651: [Lilliput/JDK17] Cherry-pick PPC parts of 8297036: Generalize C2 stub mechanism

[Roman Kennke]

We already have back-ported the majority of 8297036: Generalize C2 stub mechanism, but are missing the PPC parts. Backporting those parts will fix PPC builds.

Testing:
 - [ ] GHA PPC

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Commit messages:
 - 8308651: [Lilliput/JDK17] Cherry-pick PPC parts of 8297036: Generalize C2 stub mechanism

Changes: https://git.openjdk.org/lilliput-jdk17u/pull/25/files
 Webrev: https://webrevs.openjdk.org/?repo=lilliput-jdk17u&pr=25&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308651
  Stats: 121 lines in 3 files changed: 63 ins; 57 del; 1 mod
  Patch: https://git.openjdk.org/lilliput-jdk17u/pull/25.diff
  Fetch: git fetch https://git.openjdk.org/lilliput-jdk17u.git pull/25/head:pull/25

PR: https://git.openjdk.org/lilliput-jdk17u/pull/25