Small fixes to build webappmanager with Qt5

Original author Teppo Pennanen <teppo.pennanen@palm.com>

Open-webOS-DCO-1.0-Signed-off-by: Jaakko Putaala <jaakko.putaala@palm.com>

Change-Id: I8573ecb71315e416f652af0df27862dd449892e5
Only set QT_QPA_PLATFORM if it is not already set

If you need to use a QPA library other than libqpalm, then set
QT_QPA_PLATFORM in the environment prior to launching LunaSysMgr and
WebAppMgr.

Open-webOS-DCO-1.0-Signed-off-by: Eric Blade <eric.blade@palm.com>

Change-Id: Ia009eb4216d7232705ac4d397c55edc66ade8ce2
We need a privileged role to allow apps to access system services

When not using a privileged role for luna-service2 our applications can't access several
system applications.

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
Add support for 'tuna' build target

Open-webOS-DCO-1.0-Signed-off-by: Roger Stringer <roger.stringer@palm.com>

Change-Id: I157f701c472d55f62c12d92ab6f2ea79bcfa5a1a