hg: jdk/sandbox: 8224645: Only test multicast interfaces if they exist

[chris.hegarty at oracle.com]

Changeset: b7ad292e686c
Author:    aeubanks
Date:      2019-05-23 10:06 -0700
URL:       http://hg.openjdk.java.net/jdk/sandbox/rev/b7ad292e686c

8224645: Only test multicast interfaces if they exist
Reviewed-by: alanb, dfuchs, chegar
Contributed-by: aeubanks at google.com

! test/jdk/java/nio/channels/DatagramChannel/BasicMulticastTests.java