The client tcp socket is leaked！

[legendwind]

As we know,when a newclickhouse::Client class instance created, it will create a tcp socket and use the socket to communicate with the CK server. If the CK server is down before creating the new Client instance, the socket is leaked after a connection exception throwed!

[Enmk]

Hi @legendwind ! Thank you for reporting an issue, a similar one was reported some time ago: #208.

Could you please check against the master, since it was already fixed (and not yet released) in #228