Deprecate the JDK-specific API for setting socket options, jdk.net.Sockets

Java SE 9 added standard methods to get/set socket options, and retrieve the per-Socket supported options. This effectively renders the JDK-specific API, jdk.net.Sockets, redundant. Most of the methods in jdk.net.Sockets ( or maybe even the whole class ) could be deprecated ( maybe even for removal ).