RFR:JDK-8021372 NetworkInterface.getNetworkInterfaces() returns duplicate hardware address

[Mark Sheppard]

Hi
  based on feedback for initial fix, an amended webrev has been created.
So, please oblige and review the fix below to address the issue in 
JDK-8021372: NetworkInterface.getNetworkInterfaces() returns duplicate 
hardware address

webrev:
http://cr.openjdk.java.net/~msheppar/8021372/webrev.01/

regressions re-run with no ill effects

regards
Mark