RFR (S): 8209700: Remove HeapRegionSetBase::RegionSetKind for a more flexible approach

[Thomas Schatzl]

Hi all,

  in the review for JDK-8208498 there has been a discussion about using
enums to indicate which types of regions can be added to a given
HeapRegionSet; looking at the code, ultimately this enum is only used
for verification, i.e. if the HeapRegionSet contains the right kind of
regions or not.

Instead of adding random enum values every time you need a new
HeapRegionSet, I refactored the code so that the existing
HRSMtSafeChecker passed to HeapRegionSet instances also gets methods
for other verification, and implemented them.

I also moved the various HRSMtSafeChecker instances to their point of
use in cpp files to imho reduce the clutter in hpp files a bit (i.e.
hide them completely in cpp files).

CR:
https://bugs.openjdk.java.net/browse/JDK-8209700
Webrev:
http://cr.openjdk.java.net/~tschatzl/8209700/webrev/
Testing:
hs-tier1-3

This change is based on JDK-8208498 that is also out for review.

Thanks,
  Thomas