RFR: 8244958: preferIPv4Stack and preferIPv6Addresses do not affect addresses returned by HostsFileNameService

[Aleks Efimov]

Hi,

The "java.net.preferIPv4Stack" and "java.net.preferIPv6Addresses" system 
properties do not affect the addresses and their order, returned by the 
HostsFileNameService provider that can be created by specifying 
"jdk.net.hosts.file" system property.
The following fix analyses the system properties and re-orders/filters 
the returned IP addresses, if needed. Plus, small clean-up changes:
http://cr.openjdk.java.net/~aefimov/8244958/00

JBS:
https://bugs.openjdk.java.net/browse/JDK-8244958

Networking tests from regression and JCK suites show no failures

With Best Regards,
Aleksei