RFR: 8135305: InetAddress.isReachable reports true when loopback interface is specified

[Rob McKenna]

Hi folks,

The recent change to isReachable (8133015: 
InetAddress.isReachable(tmout) returning wrong value on Windows for IPv6 
- http://hg.openjdk.java.net/jdk9/jdk9/jdk/rev/59ff6cd9535d) neglected 
to take the specified interface into account for ipv4.

This change ensures that isReachable returns false for external hosts 
when the loopback interface is specified.

http://cr.openjdk.java.net/~robm/8135305/webrev.01/

	-Rob