RFR: 8264873: Dependencies: Split ClassHierarchyWalker [v3]

[Vladimir Ivanov]

> Split ClassHierarchyWalker into ConcreteMethodFinder and ConcreteSubtypeFinder.
> 
> Testing:
> - [x] hs-tier1 - hs-tier4

Vladimir Ivanov has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 11 commits:

 - Merge branch 'master' into 8264873.cha.split
 - Fix formatting
 - Split ClassHierarchyWalker into ConcreteMethodFinder and ConcreteSubtypeFinder
 - CountingClassHierarchyIterator
 - Migrate to PerfData
 - Depenencies perf counters
 - KlassDepChange::involves_context
 - KlassDepChange::_new_type
 - Dependencies::is_concrete_method
 - Dependencies::verify_method_context
 - ... and 1 more: https://git.openjdk.java.net/jdk/compare/76bd313d...e38b995c

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Changes: https://git.openjdk.java.net/jdk/pull/3387/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3387&range=02
  Stats: 437 lines in 1 file changed: 134 ins; 144 del; 159 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3387.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3387/head:pull/3387

PR: https://git.openjdk.java.net/jdk/pull/3387