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

[Mark Sheppard]

Hi
please oblige and review the fix below to address the issue in JDK-8021372:
NetworkInterface.getNetworkInterfaces() returns duplicate hardware address

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

the handling of the Ipv6IfIndex was suspect when setting the
interface index and when retrieving the mac address using the index.

in the getAdpaters function, the conditaionalstatement could be rolled 
into one.
But, as there was a spurious IPv4 comment, I structured it as an if 
else. statement.

It should be noted that IfIndex and the Ipv6IfIndex can be zero, which 
implies that the
IPv4 or IPv6 interface is not available. This may be at odds with the
setting of a default index to 0 in the Java NetworkInterface abstraction,
where a defaultIndex of zero is used.

JPRTs have been run and show no side effects.

regards
Mark