Fix qbs build on Windows.

Change-Id: Idc471dd4a9734f71e615532a4d70225435452d27
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
DeviceApplicationRunner: Set failure status if process failed to start.

The current code erroneously reports success in that case.

Change-Id: Ica9768ad029c76cc1103b21c963354806917b149
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>