Initialize now just takes the handle directly. Reinitialize is added because it is much more straightforward in comparison to doing the Shutdown-Initialize manually.
Yes, this is a fancy new feature, but our Wayland support was
particularly bitrotten, and ideally this would be handled by a platform
layer like SDL. If not, we can always add this back in when GLInterface
has caught up. We might be able to even support wxWidgets and GL
together with subsurfaces!
It was broken by e15ec56bf0 because it wasn't deemed important. However chances are people will eventually start using Dolphin on that configuration, so we shouldn't frivolously drop compatibility without good reason.