RFR (M): 8227739: Merge cost predictions for scanning cards and log buffer entries

[Thomas Schatzl]

Hi all,

   can I have reviews for this change that aligns the cost predictions 
to the way we do evacuations, i.e. that we first drop all remembered 
sets onto the card table, and only a fraction of that will be scanned as 
introduced by JDK-8213108.

This code adds all the predictions for ratios etc to align to that code 
in our prediction model too.

After this change (and all previous) changes just sent out for review, 
mostly JDK-8228609 (which is a prerequisite for this change), 
predictions are a bit (noticably) better than before :)

CR:
https://bugs.openjdk.java.net/browse/JDK-8227739
Webrev:
http://cr.openjdk.java.net/~tschatzl/8227739/webrev/
Testing:
hs-tier1-5, perf testing, pause time keeping improves a little

Thanks,
   Thomas