RFR: 8257498: Remove useless skeleton predicates [v5]

[Christian Hagedorn]

> This enhancement removes useless skeleton predicates in the same way as we already remove normal useless predicates in `PhaseIdealLoop::eliminate_useless_predicates()`.
> 
> Thanks,
> Christian

Christian Hagedorn has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:

 - Merge master due to conflict
 - Revert get_skeleton_predicates again
 - Fix removal from global list and update get_skeleton_predicates
 - Add handling of Deoptimization::Reason_profile_predicate
 - 8257498: Remove useless skeleton predicates

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Changes: https://git.openjdk.java.net/jdk/pull/2075/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2075&range=04
  Stats: 102 lines in 6 files changed: 67 ins; 16 del; 19 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2075.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2075/head:pull/2075

PR: https://git.openjdk.java.net/jdk/pull/2075