RFR(S): 8151637: Move CollectionSetChooser rebuild code into CollectionSetChooser

[Mikael Gerdin]

Hi all,

Currently when the CSetChooser needs to be injected with new regions the 
collector policy is responsible for calling a bunch of semi internal 
functions on the chooser and setting up some closures which are only 
relevant to the cset chooser.
I've moved that code into the collection set chooser instead.

I wasn't entirely clear on how the API for rebuild() should look since 
under the hood the closures go and access the G1CollectedHeap instance 
through the static in order to access the heap iteration method but 
since that has not changed in this patch I've left it as is.

Bug: https://bugs.openjdk.java.net/browse/JDK-8151637
Webrev: http://cr.openjdk.java.net/~mgerdin/8151637/webrev.0/
Testing: JPRT

Thanks
/Mikael