[jdk8u-dev] RFR: 8283672: Cleanup: Remove some unused flags/code in loop optimizations

[Yi Yang]

We encountered this problem in downstream JDK. This is a backport of JDK-8283672, which simply removes several diagnostic flags, build passed. There is a related fix https://bugs.openjdk.java.net/browse/JDK-8159715, I would backport it after the current fix merged.

Original changeset: http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/a1e41855499b

Please help review it.

Thanks.

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Commit messages:
 - 8283672: Cleanup: Remove some unused flags/code in loop optimizations

Changes: https://git.openjdk.java.net/jdk8u-dev/pull/22/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk8u-dev&pr=22&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8283672
  Stats: 406 lines in 7 files changed: 49 ins; 241 del; 116 mod
  Patch: https://git.openjdk.java.net/jdk8u-dev/pull/22.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk8u-dev pull/22/head:pull/22

PR: https://git.openjdk.java.net/jdk8u-dev/pull/22