Point-to-point interface should be excluded from java/net/ipv6tests/*

utun0 is introduced by "Back to My Mac". Its ipv6 address looks to be problematic.

For instance, I can use bind/connect to "en0" via socket. Or ping6.
But ping6 to utun0 address prompts " No route to host". I didn't add ip mapping to /etc/hosts.

So I think it is necessary to exclude such interface in ipv6 tests.
Found with self-built development builds and also reproduced with JDK 10 b37 promoted build.


Test output (removed real address):

binding to /[xxxx_ipv6_addr]%utun0:0
----------System.err:(23/1526)----------
java.net.ConnectException: Operation timed out (Connection timed out)
at java.base/java.net.PlainSocketImpl.socketConnect(Native Method)
at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:400)
at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:243)
at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:225)
at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:402)
at java.base/java.net.Socket.connect(Socket.java:591)
at java.base/java.net.Socket.connect(Socket.java:540)
at java.base/java.net.Socket.<init>(Socket.java:436)
at java.base/java.net.Socket.<init>(Socket.java:246)
at TcpTest.test2(TcpTest.java:142)
at TcpTest.main(TcpTest.java:66)