RFR: 8222986: Add parameter to skip clearing CHeapBitMaps when resizing

[Per Liden]

Looks good!

One minor thing, the comments in the header file still says the memory 
will be cleared. Should we change that to "optionally cleared" or 
something similar?

/Per

On 04/25/2019 08:36 PM, Stefan Karlsson wrote:
> Hi all,
> 
> Please review this patch to add a 'clear' parameter to the CHeapBitMap 
> initialize, resize, and reinitialize functions.
> 
> https://cr.openjdk.java.net/~stefank/8222986/webrev.01/
> https://bugs.openjdk.java.net/browse/JDK-8222986
> 
> We want this functionally for the ZUncommit feature, where we now split 
> ZPages and resize the bitmaps. These bitmaps are cleared lazily, so we 
> don't want to also clear them when they are resized.
> 
> Thanks,
> StefanK