Revert "Dump the current work for DispmanX-based WaylandCompositor"

This reverts commit 72c55871c7693d983a8dbbd55ebcbae63b80e739.

Revert the DispmanX compositor addition. This will be readded once
all the Wayland compositor refactoring patches are applied.
WaylandCompositor cleanup.
Manage the NestedDisplay through std::unique_ptr.
Initialize NestedSurface's bufferRef.buffer to nullptr.
Clean up WaylandDisplay.
Clean up WaylandSurface, a bit.
Fix a typo.
Fix up WaylandDisplay::instance().
Fix a tpyo in NestedSurface dtor -- source -> surface.
Generate the texture in NestedSurfaceEGL ctor.
Remove the FPS counter code. Not vital.
Add (back) WaylandCompositor::widgetID() that retrieves GtkWidget's wayland-compositor-widget-id data.
Initialize destroyListener.link in the NestedBuffer ctor.
Initialize the buffer, widget, link members in NestedSurface ctor.
Initialize the link member in the NestedFrameCallback ctor.
Fold NestedDisplay into WaylandCompositor.
Add the WaylandCompositorDispmanX class.
Remove an invalid semicolon.
Fix uses of WaylandDisplay::nativeDisplay().
Don't dereference the inlined m_display struct in WaylandCompositorDispmanX.