Refactor MulticastSocketTest to JUnit 4.

This is a pre-requisite for converting
        if (!supportsMulticast) {
            return;
        }
to:
        Assume.assumeTrue(supportMulticast);

which I intend to do in a follow-up CL.

Test: atest CtsLibcoreTestCases:org.apache.harmony.tests.java.net.MulticastSocketTest
Bug: 151612773
Change-Id: Ic2d7381936617cad1bc6144e89ab1ba087b04831
1 file changed