wayland-pointer: fix condition for grabbing

It returns FALSE when button_count is not 0. But grabbing for
move/resize is activated by clicking the button, so this condition
disallows the wayland clients to be moved/resized.

https://bugzilla.gnome.org/show_bug.cgi?id=731237
wayland window: update buffer_rect when moving

Update both - rect and buffer_rect positions when moving wayland window

https://bugzilla.gnome.org/show_bug.cgi?id=731237