Fix copy() in SVCBIPv4Hint and SVCBIPv6Hint (#1256)
Fix copy() in SVCBIPv4Hint and SVCBIPv6Hint (#1256)

* Fix copy() in SVCBIPv4Hint and SVCBIPv6Hint

The problem with the current implementation is that it is not a real deep copy,
it points to the same base arrays behind the slices. This was causing some
issues in real-life application.

* Address review comments
miekg/dns