RFR: 8378675: PPC64: increase instruction cache line size [v3]

[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).

David Briemann has updated the pull request incrementally with one additional commit since the last revision:

  remove comments, fix comparison

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/29918/files
  - new: https://git.openjdk.org/jdk/pull/29918/files/bb0973c1..dfa4bbf9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29918&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29918&range=01-02

  Stats: 4 lines in 1 file changed: 0 ins; 2 del; 2 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