RFR: 8253029: [PPC64] Remove obsolete Power6 code [v3]

[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 refreshed the contents of this pull request, and previous commits have been removed. The incremental
views will show differences compared to the previous content of the PR.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/116/files
  - new: https://git.openjdk.java.net/jdk/pull/116/files/f820714a..ff21696b

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=116&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=116&range=01-02

  Stats: 934 lines in 5 files changed: 899 ins; 0 del; 35 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