SDL_WINDOWEVENT_SIZE_CHANGED should be used instead of SDL_WINDOWEVENT_RESIZED
because SDL_WINDOWEVENT_RESIZED is only emitted if the resize happened due to
an external event.

Fixes ticket #8072.

Additional references:
https://bugzilla.libsdl.org/show_bug.cgi?id=4760
https://wiki.libsdl.org/SDL_WindowEventIDSigned-off-by: Marton Balint <cus@passwd.hu>