xio: replace a cout with dout in on_msg_error

Signed-off-by: Casey Bodley <casey@linuxbox.com>
xio: remove unneeded xio_query_connection

event_data->conn_user_context is already passed with
XIO_SESSION_CONNECTION_ESTABLISHED_EVENT, so the call to
xio_query_connection() is redundant

Signed-off-by: Casey Bodley <casey@linuxbox.com>
xio: fix for xio_msg_buffer dtor

the completion hook can't be freed until the overloaded delete operator,
so the call to put() was moved there

Signed-off-by: Casey Bodley <casey@linuxbox.com>
cmake: add WITH_TEST option

Signed-off-by: Casey Bodley <casey@linuxbox.com>