RFR (XS) 8025550 valgrind: Conditional jump depends on uninitialised value in Arena::set_size_in_bytes()

[Coleen Phillimore]

This looks good.  Sorry for the delay, especially since the change is 
simple.
Coleen

On 2/25/14 12:43 PM, Zhengyu Gu wrote:
> This is a simple fix to NMT, which can mis-count arena size due to uninitialized  value. In rare case, if uninitialized size happens to be the same value as arena's initial size, NMT will mis-count the size, since NMT only updates size when the new size does not equal to the old one.
>
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8025550
> Webrev:  http://cr.openjdk.java.net/~zgu/8025550/webrev.00/
>
> Thanks,
>
> -Zhengyu