RFR 8085875/10, java/net/DatagramSocket/PortUnreachable.java fails intermittently: Address already in use

[Felix Yang]

Hi all,

     please review a patch to add retries to avoid possible port 
conflicts during re-binding.

Bug:

     https://bugs.openjdk.java.net/browse/JDK-8085875

Webrev:

     http://cr.openjdk.java.net/~xiaofeya/8085875/webrev.00/

Thanks,

Felix