[lilliput-jdk17u:lilliput] RFR: 8308680: [Lilliput/JDK17] Add missing LoadKlassStub skeletons

[Roman Kennke]

Arm, PPC and s390 ports are missing the skeletons for LoadKlassStub::emit_code(), which breaks those builds.

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Commit messages:
 - Merge branch 'lilliput' into JDK-8308680
 - Remove duplicate emit_load_klass() in s390; Add missing LoadKlassStub in arm, ppc and s390
 - 8308680: Cherry-pick s390 parts of 8277417: C1 LIR instruction for load-klass

Changes: https://git.openjdk.org/lilliput-jdk17u/pull/26/files
 Webrev: https://webrevs.openjdk.org/?repo=lilliput-jdk17u&pr=26&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308680
  Stats: 10 lines in 3 files changed: 10 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/lilliput-jdk17u/pull/26.diff
  Fetch: git fetch https://git.openjdk.org/lilliput-jdk17u.git pull/26/head:pull/26

PR: https://git.openjdk.org/lilliput-jdk17u/pull/26