If we're already trying to connect when the "Waiting for ..." message
arrives we don't want to start from scratch, but rather reuse the
existing connection.

Otherwise the handshake may be interrupted in an arbitrary state,
either leaving the remote QML engine waiting for the local QML profiler
to send the recording status, or prompting the local profiler client to
stop recording as the connection "broke".

The local QML profiler will only send the recording status if new QML
engines show up, which doesn't happen on the second successful
connection. That may be a different bug.

Change-Id: Ia17fcf9d0a28edf700274bcd88c2b7030220c290
Reviewed-by: Robert Loehning <robert.loehning@theqtcompany.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>