RFR: 8266973: Migrate to ClassHierarchyIterator when enumerating subclasses [v2]

[Coleen Phillimore]

On Thu, 13 May 2021 09:36:40 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Replace ad-hoc recursion when enumerating subclasses with `ClassHierarchyIterator`.
>> 
>> Found 3 occurrences:
>> - `Dependencies::find_finalizable_subclass()`
>> - `reinitialize_vtable_of()`
>> - `VM_RedefineClasses::increment_class_counter()`
>> 
>> Testing:
>> - [x] hs-tier1 - hs-tier4
>
> Vladimir Ivanov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   JFR

good also!

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Marked as reviewed by coleenp (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/3995