in tls_call_connect_cb(), we want to update the result for
the TLS socket. however, in some error conditions on connect,
the handle we're passing is for the TCP socket instead. this
was causing the wrong socket's result code to be updated, and
the thread that was waiting for the result to be updated never
woke up.
(note: while the fix in this commit causes doh_test to stop
deadlocking, I'm not sure whether I've actually fixed the bug.
in other places, we create a new 'tlshandle' to pass into
tls_call_connect_cb(). perhaps we should be doing that in
all cases?)
incidentally, I also renamed tls_connect_cb() to tcp_connected(),
because the handle passed in is for the TCP socket, and I kept
being confused by the name having "tls" in it.
8ea2cd7864