RFR: 8253029: [PPC64] Remove obsolete Power6 code [v2]

[Martin Doerr]

> 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.

Martin Doerr has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev
excludes the unrelated changes brought in by the merge/rebase. The pull request contains one additional commit since
the last revision:

  Remove obsolete Power6 code

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/116/files
  - new: https://git.openjdk.java.net/jdk/pull/116/files/a4e2ecff..f820714a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=116&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=116&range=00-01

  Stats: 207 lines in 10 files changed: 50 ins; 10 del; 147 mod
  Patch: https://git.openjdk.java.net/jdk/pull/116.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/116/head:pull/116

PR: https://git.openjdk.java.net/jdk/pull/116