Fix input and bounding shapes

For decorated windows, we don't want to apply any input
shape, because the frame is always rectangular and eats
all the input.
The real check is in meta-window-actor, where we consider
if we need to apply the bounding shape and the input shape
(or the intersection of the two) to the surface-actor,
but as an optimization we avoid querying the server in
meta-window.
Additionally, for undecorated windows, the "has input shape"
check is wrong if the window has a bounding shape but not an
input shape.
MetaWindowX11: fix listening for shape events

This code was lost when support for input shapes was originally
introduced.