RFR: 8035057: NewSize ergonomics wrong when setting small or unaligned size on command line

[Stefan Johansson]

Hi,

Can I please have some reviews for this small fix for:
https://bugs.openjdk.java.net/browse/JDK-8035057

Webrev:
http://cr.openjdk.java.net/~sjohanss/8035057/

Summary:
When fixing JDK-8033426, the case when NewSize is set on the command 
line but not aligned was not handled. This small change makes sure that 
if NewSize is given on the command line we will align the value and use 
it as both initial and minimum young generation size.

Testing:
* Build on JPRT.
* Manual sanity testing.

Thanks,
Stefan