RFR: 8253029: Remove obsolete Power6 code

Fri Sep 11 10:29:05 UTC 2020

New pull request:
Using a branch, updated Copyright, removed some more unused code.

[Previous text]
The recent PPC64 platform files still contain code which is part of a Power6 optimization called Power6Scheduler.
However, this functionality was never completely contributed so it was never usable in the OpenJDK. We should remove it
since we're no longer optimizing for Power6.

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

Commit messages:
 - Remove obsolete Power6 code

Changes: https://git.openjdk.java.net/jdk/pull/127/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=127&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253029
  Stats: 936 lines in 5 files changed: 0 ins; 899 del; 37 mod
  Patch: https://git.openjdk.java.net/jdk/pull/127.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/127/head:pull/127

PR: https://git.openjdk.java.net/jdk/pull/127