x11: Avoid updating focus on wayland compositor

Reading upon the history of this code branch (commits 6891ce95 and 7a4c808e are most relevant), it seems this code is meant to synchronize Mutter focus state taking the Xserver state as true. That is, if Mutter tried to change the focus but something truncated that action, Mutter focus will be changed to be in sync with the Xserver again.

This sounds backwards in a Wayland session. Mutter focus should be the canonical source, and not second-guessed from the current Xserver focus window.

An example of this breaking can be reproduced with a Spotify and Firefox window, moving the focus from the first to the second by going to the GNOME Shell overview in between, and clicking the Firefox window from there. The Firefox window will be raised, but refuse to take focus.

It's unclear what made this an issue recently, perhaps commit 0e6395d9 since the now possibly ignored XI_FocusIn/Out events affect this accounting of the Xserver focused window. Anyhow it sounds better to ignore these paths for Wayland/native altogether.