RFR: 8146399: Refactor the BlockOffsetTable classes.

[David Lindholm]

Hi,

Please review the following patch which refactors the Block Offset Table 
classes in G1.

Right now there are 3 classes which are responsible for a part of the 
Block Offset Table. These are G1BlockOffsetArrayContigSpace, which 
inherits from G1BlockOffsetArray which inherits from G1BlockOffsetTable. 
I have merged these 3 classes into a new one called 
G1BlockOffsetTablePart, removing some dead code.

The class responsible for the whole BOT has been renamed from 
G1BlockOffsetSharedArray to G1BlockOffsetTable.

Also, the class called G1OffsetTableContigSpace has been renamed to 
G1ContiguousSpace.

Bug: https://bugs.openjdk.java.net/browse/JDK-8146399
Webrev: http://cr.openjdk.java.net/~david/JDK-8146399/webrev.00/

Testing: JPRT and vm.gc testlist.


Thanks,
David