window: Fix build once more

Bad syntax here...
window: Delay the showing of XWayland clients until set_window_id

Use our new "surface_mapped" field to delay the showing of XWayland clients
until we have associated together the window's XID and the Wayland surface ID.

This ensures that when we show this window to the compositor, it will properly
use the Wayland surface for rendering, rather than trying to use COMPOSITE and
crash.

https://bugzilla.gnome.org/show_bug.cgi?id=720631
window: Centralize WM_STATE management
window-x11: Move meta_window_new to window-x11.c and rename