GDK W32: send both smooth and discrete scrolling events
Commit 359df028 changed the
code to send GDK_SCROLL_SMOOTH
with deltas instead of
GDK_SCROLL_(UP|DOWN|LEFT|RIGHT)
. Change it again, to send
both the GDK_SCROLL_SMOOTH
and the GDK_SCROLL_(UP|DOWN|LEFT|RIGHT)
event separately, as this is what other backends (such as wayland) do.