cursor: Do not clamp motion coordinates for XWayland surfaces.

cursor: Do not clamp motion coordinates for XWayland surfaces.

X11 apps expect to be able to receive motion events outside
the window area (this is necessary for client-side move/resize
handles to work properly).  So do not clamp the motion
coordinates for XWayland surfaces.

Before this change, attempting to enlarge an XWayland window
using a client-side resize handle resulted in the window size
lagging behind the mouse cursor quite severely, since each
motion event was in effect allowed to expand the window by
only a few pixels.  The closer the initial button-press was
to the edge of the window, the worse the lag would be.