sdl2: Use correct sdl2_console for window events

sdl2: Use correct sdl2_console for window events

SDL_PollEvent() polls events for all windows; therefore,
sdl2_poll_events() will poll the events for all windows and not only for
the one identified by the given sdl2_console.

This should be considered in handle_windowevent(): The window affected
by the event is not necessarily the one identified by the sdl2_console
object given to sdl2_poll_events(), but the one identified by
ev->window.windowID.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>