events: Remove an overzealous ifdef
pointer: Make coding style similar to keyboard
window-wayland: Always update the last_sent size

The last_sent size is effectively what size we should send in configure
requests where the size hasn't changed. Thus, if an app commits a new
size, we need to make sure we respect it and don't reconfigure it with
a size it wasn't expecting when the state changes.

This fixes apps being sent a configure event with 0, 0 on startup,
which was confusing Clutter into displaying a 0x0 viewport.