Indicate that QTestLib is running

Set QT_QTESTLIB_RUNNING=1 on QTestLib startup.

This allows Qt to adapt its behavior to the testing
environment, WHICH IS NORMALLY NOT SOMETHING YOU WANT
TO DO. Use with caution.

Change-Id: I31de80e7c2cc91ff1ed8137926e6b729ef6efdc6
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
QPrinter - Fix DuplexMode on all platforms

Add support to get/set the DuplexMode on Windows and Mac, improve the
CUPS duplex handling, ensure support is the same on all platforms.

[ChangeLog][QtPrintSupport][QPrinter] Added duplex support for Windows
and OS X.

Task-number: QTBUG-11332
Change-Id: I9d61d63233d828c3b1fd6df54072c6049f3c6298
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>