Add a test for QLocalSocket::open

This should have been done in the commit that introduced open
(953255abab0f99afe7559da93ba18a876805d78d), but was missing.

Change-Id: I1c2de4ad5fa42aa5b90646e7d4d7d1b1570a0f87
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Fix incomplete override of QIODevice::open in QProcess and QLocalSocket

The rule for a new override is that it must still work if the old
implementation is called. The catch is that any class that derives from
QProcess and isn't recompiled will still have QIODevice::open in its
virtual table. That is equivalent to overriding open() and calling
QIODevice::open() (like the tests).

In Qt 5.0, QProcess::start() called QIODevice::open directly, not the
virtual open(), so there's no expectation that a user-overridden open()
be called. With that in mind, simply fix QProcess::start to not call the
virtual open at all.

Similarly with QLocalSocket, the calls to open were always non-virtual.

Task-number: QTBUG-32284
Change-Id: I88925f0ba08bc23c849658b54582744997e69a4c
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Ignore or suppress warning and debug messages in tst_QLocalSocket

The one in tst_QLocalSocket::writeToClientAndDisconnect just needed
proper ordering: that's what waitForDisconnect is for. At the same time,
we need to make sure we get the same message from all three
implementations of QLocalSocket::waitForDisconnect (and without the
useless space at the end).

Change-Id: I21364263cf908df022df814a6a39fcb5783e84e6
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>