desktop-shell: don't allow negative values in drag resize

Now clamping width and height to a minimum of 1, 1 when drag resizing.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Jasper St. Pierre <jstpierre@mecheye.net>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>

desktop-shell/shell.c

@@ -1838,6 +1838,10 @@ resize_grab_motion(struct weston_pointer_grab *grab, uint32_t time,
 		height += wl_fixed_to_int(to_y - from_y);
 	}
 
+	if (width < 1)
+		width = 1;
+	if (height < 1)
+		height = 1;
 	shsurf->client->send_configure(shsurf->surface, width, height);
 }