RFR: 8181317: SA: Enable corefile debugging on Portola for gcore dumped files

[Jini George]

Requesting a review for a very small change to avoid an address conflict 
check for enabling core file debugging on Portola for gcore generated 
corefiles.

https://bugs.openjdk.java.net/browse/JDK-8181317
Webrev: http://cr.openjdk.java.net/~jgeorge/8181317/webrev.00/

The analysis has been detailed in the bug.

Thanks,
Jini.