RFR: 8274662: Replace 'while' cycles with iterator with enhanced-for in jdk.hotspot.agent

[Alex Menkov]

On Wed, 22 Sep 2021 08:58:01 GMT, Andrey Turbanov <github.com+741251+turbanoff at openjdk.org> wrote:

> There are few places in code where manual `while` loop is used with Iterator to iterate over Collection.
> Instead of manual `while` cycles it's preferred to use _enhanced-for_ cycle instead: it's less verbose, makes code easier to read and it's less error-prone.
> It doesn't have any performance impact: javac compiler generates similar code when compiling enhanced-for cycle.
> 
> Similar cleanups:
> * https://bugs.openjdk.java.net/browse/JDK-8258006
> * https://bugs.openjdk.java.net/browse/JDK-8257912

Marked as reviewed by amenkov (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/5630