For non-blocking sockets tls_connect_fds() could fail with EAGAIN.

For non-blocking sockets tls_connect_fds() could fail with EAGAIN.
Use the same logic from the read, write, accept functions to inform
the caller wether a readable or writable socket is needed.  After
that event, the connect function must be called again.  All the
checks before connecting are done only once.
OK tedu@