[8u20] Backport RFR: JDK-8033426: Scale initial NewSize using NewRatio if not set on command line

[Stefan Johansson]

Hi,

I want to backport JDK-8033426 to solve the regression in jdk-8 where 
the default young generation size is always the same as the minimum 
generation size for the generational collectors.

The backport applied clean except for the testing parts in jni.cpp, 
where another test-call had moved. The backport webrev is available at:
http://cr.openjdk.java.net/~sjohanss/8033426/backport.00
The original jdk9 change:
http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/f7f0c6a77d6d

As a follow up on this backport I also plan to backport JDK-8035057, 
which fixes a problem with unaligned sizes introduced by this fix. That 
change applies clean, here is the jdk9 change:
http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/bac9ef65b71d

Jon and Jesper, you reviewed this the last time. Would you please have a 
quick look and see if you think everything is ok.

Thanks,
Stefan