make Wayland the default

[Milli189]

What should happen

I've seen from some bug reports here that PPSSPP supports Wayland, and I'd like it to be the default automatically when I'm using a Wayland session, because right now it defaults to x11.

Who would this benefit

Better compatibility and less issues on Wayland

Platform (if relevant)

Linux / BSD

Games this would be useful in

Every game

Other emulators or software with a similar feature

RPCS3 defaults to Wayland

Checklist

• Check the latest git build in case it's already implemented.
• Search for other requests of the same feature.