These previously mapped SIZEALL to "move", but "move" is not guaranteed
to be a four-pointed arrow: according to the CSS spec, it's actually
intended to be a drag-and-drop cursor, analogous to "alias" and "copy".
Map it to "all-scroll" instead, as in Wayland: while this is *also* not
semantically guaranteed to be a four-pointed arrow, it is at least
*suggested* to make it a four-pointed arrow.
Signed-off-by: Simon McVittie <smcv@collabora.com>
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