Teach App4Test how to understand WM_CLOSE

On windows, the `--launcher-timeout` test is currently disabled . Indeed, in that case, the function [QProcess::terminate()](http://doc.qt.nokia.com/4.7-snapshot/qprocess.html#terminate) sends a `WM_CLOSE` event and our `App4Test` doesn't handle it.

It may be possible to use [SetConsoleCtrlHandler](http://msdn.microsoft.com/en-us/library/windows/desktop/ms686016%28v=vs.85%29.aspx)
