Motivation:
We see occational failures in the datagram tests saying 'address already
in use' when we attempt to bind on a port returned by
TestUtils.getFreePort().
It turns out that TestUtils.getFreePort() only checks if TCP port is
available.
Modifications:
Also check if UDP port is available, so that the datagram tests do not
fail because of the 'address already in use' error during a bind
attempt.
Result:
Less chance of datagram test failures
582f2e82ec