https://github.com/rust-windowing/softbuffer/issues/41
If `set_buffer` can just be called in a loop without waiting for buffers
to be released or a frame callback, but can also be called in other
ways, I don't know if there's a better solution than blocking.
Should fix https://github.com/rust-windowing/softbuffer/issues/48. The
animation example could probably be implemented better, but this is at
least better.
I guess it should be documented that `set_buffer` may block? I don't
know how this compares to other backends.
Also updates `winit` example to redraw on resize, which seems to be
necessary.
With this resizing seems to be entirely smooth, without visual
corruption from it overwriting the buffer the server is displaying.