RFR (S): 8211388: Make OtherRegionsTable independent of the region it is for

[Thomas Schatzl]

Hi,

  the OtherRegionsTable is a set of a set of cards that comprises the
remembered set.

It stores the HeapRegion it collects cards for to do filtering in the
FromCardCache. The set of cards should not have knowledge about what
region it is for, from an abstraction POV it should just be a dumb
container of cards.

Move out the HeapRegion id from OtherRegionsTable (the "set of cards")
into the enclosing HeapRegionRememberedSet (managing set of cards),
separating the FCC functionality from the raw data storage.

This will make code that assigns a HeapRegionRememberedSet to multiple
regions in the future a bit simpler too.

CR:
https://bugs.openjdk.java.net/browse/JDK-8211388
Webrev:
http://cr.openjdk.java.net/~tschatzl/8211388/webrev/
Testing:
hs-tier1-3

Thanks,
  Thomas