Load DPMSAction only on xcb platform
Review Request #124318 - Created July 10, 2015 and submitted
The DPMS action is implemented in a very x11 specific way calling into xcb in the ctor and before supported can be checked. This causes a crash on platforms != xcb. In order to better support other platforms the action is marked as xcb specific in the desktop file and the loading of Actions is adjusted to only load Actions supported on the current platform.
No longer crashes in a Plasma/Wayland session.