Exception based memory based eviction doesn't work with segmented OffHeap

When segmented off heap was added the exception based memory eviction wasn't updated to properly gauge how large the underlying maps are in size. It currently just adds a size for one map, and it should change based on how many maps there are. ISPN-10574 is also introducing resizing maps, which will also need to be accounted for. Both of these issues should be resolvable using the same mechanism, which would require being able to talk to the underlying maps in some fashion.