RFR: 8255990: Bitmap region of dynamic CDS archive is not unmapped

[Calvin Cheung]

On Wed, 11 Nov 2020 00:06:02 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Add the missing call to `unmap_region` to unmap the bitmap region of a dynamic CDS archive.
>> 
>> Also modify the `DynamicArchiveRelocationTest` to check for the "Unmapping region" message.
>> 
>> Testing:
>> 
>> - [x] tier1
>> - tiers 2,3,4 (in progress)
>
> LGTM

@iklam, @yminqi, Thanks for your reviews!

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PR: https://git.openjdk.java.net/jdk/pull/1151