RFR: 8378675: PPC64: increase instruction cache line size

[David Briemann]

Set the instruction cache line size for Power to 128 bytes.

Add functions to retrieve the data cache line size and instruction cache line size from the system (AIX & Linux).

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Commit messages:
 - 8378675: PPC64: increase instruction cache line size

Changes: https://git.openjdk.org/jdk/pull/29918/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29918&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8378675
  Stats: 62 lines in 8 files changed: 34 ins; 22 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/29918.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29918/head:pull/29918

PR: https://git.openjdk.org/jdk/pull/29918