RFR(S): 8026396 - Remove information duplication in the collector policy

[Jesper Wilhelmsson]

Hi,

Another step towards cleaner collector policy code.

This cleanup removes the need to keep the generation sizing flags in sync with 
the collector policy version of the same variables during setup. The collector 
policy variables are initialized in the start and then used throughout the setup 
code. In the end we write the values back to the flags if needed.

This change builds upon the merged collector policy (8027643) currently in review.

Webrev: http://cr.openjdk.java.net/~jwilhelm/8026396/webrev/

Bug: https://bugs.openjdk.java.net/browse/JDK-8026396

Thanks,
/Jesper