dpms: Add support for DPMSInfoNotify event from DPMS 1.2 (xorgproto)
This allows applications to respond to changes of power level of a monitor, e.g. an application may stop rendering and related calculations when the monitor is off.
Related bug: https://bugs.freedesktop.org/57120
Signed-off-by: Alexander Volkov a.volkov@rusbitech.ru