RFR: 8277336: Improve CollectedHeap::safepoint_workers comments

[Albert Mingkun Yang]

On Wed, 17 Nov 2021 15:32:58 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Simple change of updating comments.
> 
> Test: build

Thanks for the review.

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PR: https://git.openjdk.java.net/jdk/pull/6432