Avoid using point-to-point interfaces in multicast socket tests

Multicast on a point-to-point interface isn't really multicast.

Bug: 23279677
(cherry-picked from commit 67d7597da46910e65a089bcce0afa8e0c2bed668)

Change-Id: Ib102e9d04744d3e99b8828ac31d9548e72b703dd
diff --git a/harmony-tests/src/test/java/org/apache/harmony/tests/java/net/MulticastSocketTest.java b/harmony-tests/src/test/java/org/apache/harmony/tests/java/net/MulticastSocketTest.java
index b6a5861..264e004 100644
--- a/harmony-tests/src/test/java/org/apache/harmony/tests/java/net/MulticastSocketTest.java
+++ b/harmony-tests/src/test/java/org/apache/harmony/tests/java/net/MulticastSocketTest.java
@@ -922,7 +922,10 @@
         return iface.isUp()
                 // Typically loopback interfaces do not support multicast, but we rule them out
                 // explicitly anyway.
-                && !iface.isLoopback() && iface.supportsMulticast()
+                && !iface.isLoopback()
+                // Point-to-point interfaces are known to cause problems. http://b/23279677
+                && !iface.isPointToPoint()
+                && iface.supportsMulticast()
                 && iface.getInetAddresses().hasMoreElements();
     }