RFR(M): 7114678: G1: various small fixes, code cleanup, and refactoring

[John Cuthbertson]

Hi Everyone,

This is the first in a series of patches that were completed by Tony 
just before he left Oracle. There will be a few more in the coming few 
weeks.

This first patch is a pre-cursor to another patch that introduces 
iterators for heap regions, and is exactly what it says in the synopsis 
(and description in the bug database). Tony sent a version of this patch 
earlier in the year; I reviewed it and Tony incorporated the feedback 
into this version. So I'm looking for a couple of volunteers to also 
review these changes. The webrev can be found at: 
http://cr.openjdk.java.net/~johnc/7114678/webrev.0/

Testing: GC Test Suite with and without some stress options, NSK tests 
(regression, gc, jit, and runtime), jprt.

Thanks,

JohnC