cppzmq deprecated function calls

[SylvainCorlay]

There are new deprecations in cppzmq 4.7.0.

We are using two deprecated methods from socket_base, namely setsockopt and getsockopt

src/xptvsd_client.cpp:42:60: warning: 'void zmq::detail::socket_base::setsockopt(int, const T&) [with T = int]' is deprecated: from 4.7.0, use `set` taking option from zmq::sockopt [-Wdeprecated-declarations]
         m_ptvsd_socket.setsockopt(ZMQ_LINGER, socket_linger);

[...]

src/xptvsd_client.cpp:58:72: warning: 'void zmq::detail::socket_base::getsockopt(int, void*, size_t*) const' is deprecated: from 4.7.0, use `get` taking option from zmq::sockopt [-Wdeprecated-declarations]
         m_ptvsd_socket.getsockopt(ZMQ_IDENTITY, m_socket_id, &m_id_size);