RFR: 8350202: Tune for Power10 CPUs on Linux ppc64le

[Matthias Baesken]

Currently we tune for older Power8 CPUs in the libjvm build, this should be adjusted to current Power10.

We do not set (yet) mcpu / mtune in the other native compilation units in the linux ppc64le build; this should we reconsidered.

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

Commit messages:
 - JDK-8350202

Changes: https://git.openjdk.org/jdk/pull/23664/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23664&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8350202
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/23664.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23664/head:pull/23664

PR: https://git.openjdk.org/jdk/pull/23664