RFR: 8327093: Add truncate function to BitMap API [v4]

[Axel Boldt-Christmas]

On Fri, 8 Mar 2024 16:51:10 GMT, Matias Saavedra Silva <matsaave at openjdk.org> wrote:

>> The BitMap does not currently have a "slice" method which can return a subset of the bitmap defined by a start and end bit. This utility can be used to analyze portions of a bitmap or to overwrite the existing map with a shorter, modified map. 
>> 
>> This implementation has two core methods: 
>> `copy_of_range` allocates and returns a new word array as used internally by BitMap
>> `truncate` overwrites the internal array with the one generated by `copy_of_range` so none of the internal workings are exposed to callers outside of BitMap.
>> 
>> This change is verified with an included test.
>
> Matias Saavedra Silva has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Fixed CV-qualifier style
>  - Axel comments and new test case

lgtm.

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Marked as reviewed by aboldtch (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18092#pullrequestreview-1927027504