After the loop manager refactoring TCP DNS and TLS DNS unit tests
ended up broken.
The problem is that in these unit tests the code is written in such a
way that for establishing a new connection tcpdns_connect() and
tlsdns_connect() functions are used. However, in these tests as a
connection callback function connect_connect_cb() is used. The
function logic is responsible for determining the function for
establishing subsequent connection.
To do so, it called get_stream_connect_function() ... which can return
only tcp_connect() or tls_connect(), not tcpdns_connect() or
tlsdns_connect(). That is definitely *not* what was implied.
All this time the unit tests were testing something, but now what was
intended.
This commit fixes the problem by passing the tcpdns_connect() and
tlsdns_connect() function pointers to connect_connect_cb().