This is another step towards making GdkDisplayManager backend-agnostic.
Most of the backends profit from this as their atom implementations
where generic anyway - x11 needed that to allow multiple X displays and
broadway, quartz and wayland don't have the concept of displays.
The X11 backend still did things, so I only #if 0'd some code but did
not actually update anything.
This just runs:
for i in *.[ch]; do
sed -i s/DisplayX11/DisplayBroadway/g $i;
sed -i s/PrivateX11/PrivateBroadway/g $i;
sed -i s/ImplX11/ImplBroadway/g $i;
sed -i s/KeymapX11/KeymapBroadway/g $i;
sed -i s/ScreenX11/ScreenBroadway/g $i;
sed -i s/GdkX11Monitor/GdkBroadwayMonitor/g $i;
sed -i s/_X11/_BROADWAY/g $i;
sed -i s/x11/broadway/g $i;
done