fix deprecation warning in qbs project files

Change-Id: Ie8f639550fa4509fbec70092fabfaf44342546f2
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>
Compile with C++11/libc++

Change-Id: I5ca0743ecef0010b07df76557e94b3913a0e2417
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
make the qbs.PropertyList extension available on all platforms

Change-Id: I4ab90b63f6139d9743a7251ff574f6b4b37e123d
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>