RFR: 8214118: HeapRegions marked as archive even if CDS mapping fails

[Stefan Johansson]

Hi,

Please review this fix to avoid leaving heap metadata in an inconsistent 
state when CDS archive mapping fails.

Issue: https://bugs.openjdk.java.net/browse/JDK-8214118
Webrev: http://cr.openjdk.java.net/~sjohanss/8214118/00/

Summary
-------
Since JDK 12b15 a default CDS archive is shipped with the JDK. If this 
archive for some reason fails to be mapped into the heap, the cleanup 
leaves the heap metadata in a inconsistent state. Instead of clearing 
the range in the map storing which regions are archive, it once again 
marks the range as archive.

This information is used by the G1 Full collections and because a 
regions is marked as archive even though it is not, we skip marking 
through this region. This causes the heap to be corrupt and we can crash 
in many different ways.

Testing
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Verified that the new code clears the map correctly and re-ran the 
benchmark previously failing many times. Tier 1-3 of normal functional 
testing also run through m5 without problems.

Thanks,
Stefan