Autotest: Disable multicast testing with proxies

It doesn't make sense because there is no command to ask the proxy
server to join a multicast group. At best, we could write a datagram via
proxy without joining, but we definitely can't receive.

Change-Id: Icc6b54572a053fb7821dfca1f4111f2046ff8686
Reviewed-by: Richard J. Moore <rich@kde.org>
Suppress silly shell warning during qmake of qtcpsocket.pro

If you don't have /etc/lsb-release, you'd get
  sh: line 0: [: =: unary operator expected

Change-Id: Idb5c79f799879e4d32cd640ef74fb388227f831e
Reviewed-by: Richard J. Moore <rich@kde.org>
Don't try to send broadcasts over IPv6

IPv6 has no such thing, so don't try to bind to an IPv6 address to send
broadcasts (even though that works) and it's a poor idea to bind to IPv6
to receive broadcasts. Moreover, skip any IPv6 network addresses
(broadcast() is invalid).

Change-Id: I2829b042c000158565adfd92db682f37d67dacae
Reviewed-by: Richard J. Moore <rich@kde.org>
Stabilize tst_QUdpSocket::broadcasting

Sending 100*8 packets of each type of message is WAY overkill. That's a
stress test without limiting. My Linux system starts reporting EAGAIN on
the socket, so reduce the amount of data sent.

Change-Id: I153f44cf3b91d37526dac580b400114cc80b1769
Reviewed-by: Richard J. Moore <rich@kde.org>
Fix silly mistake: 0 is a valid file descriptor

Change-Id: I60baa01f0ef9419a73535c761c4722c5abd6f26e
Reviewed-by: Richard J. Moore <rich@kde.org>