RFR: 8376113: PPC64: Implement special MachNodes for floating point Min / Max

[David Briemann]

Add mach nodes MinF, MaxF, MinD, MaxD for PPC.

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Commit messages:
 - 8376113: PPC64: Implement special MachNodes for floating point Min / Max

Changes: https://git.openjdk.org/jdk/pull/29361/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29361&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8376113
  Stats: 57 lines in 3 files changed: 57 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/29361.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29361/head:pull/29361

PR: https://git.openjdk.org/jdk/pull/29361