Copy IPAddressUtil to avoid accessing private sun package

[pan3793]

The newer JDK restricts accessing sun and other private packages, we get the following error when upgrading from JDK 8 to JDK 17.

class net.ipip.ipdb.Reader (in unnamed module @0x435cf50d) cannot access class sun.net.util.IPAddressUtil (in module java.base) because module java.base does not export sun.net.util to unnamed module @0x435cf50d